1 Boston data

library(MASS)
library(DT)
datatable(Boston, rownames = FALSE)

1.1 Split into train and test

set.seed(3416)
library(caret)
Loading required package: ggplot2
Loading required package: lattice
TRAIN <- createDataPartition(Boston$medv,
                             p = 0.75,
                             list = FALSE,
                             times = 1)
BostonTrain <- Boston[TRAIN, ]
BostonTest <- Boston[-TRAIN, ]

1.2 Pre-process the data

pp_BostonTrain <- preProcess(BostonTrain[, -14],
                           method = c("center", "scale", "BoxCox"))
pp_BostonTrain
Created from 381 samples and 13 variables

Pre-processing:
  - Box-Cox transformation (11)
  - centered (13)
  - ignored (0)
  - scaled (13)

Lambda estimates for Box-Cox transformation:
   Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
-0.9000 -0.1500  0.3000  0.4455  0.9500  2.0000 
BostonTrain_pp <- predict(pp_BostonTrain, newdata = BostonTrain)
datatable(BostonTrain_pp, rownames = FALSE)
#
pp_BostonTest <- preProcess(BostonTest[, -14],
                           method = c("center", "scale", "BoxCox"))
pp_BostonTest
Created from 125 samples and 13 variables

Pre-processing:
  - Box-Cox transformation (11)
  - centered (13)
  - ignored (0)
  - scaled (13)

Lambda estimates for Box-Cox transformation:
   Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
-0.9000 -0.1500  0.1000  0.3636  0.7500  2.0000 
BostonTest_pp <- predict(pp_BostonTest, newdata = BostonTest)
datatable(BostonTest_pp, rownames = FALSE)

1.3 Linear model

set.seed(123)
library(caret)
myControl <- trainControl(method = "cv", number = 5)
mod_lm <- train(medv ~ ., 
                data = BostonTrain_pp,
                trControl = myControl,
                method = "lm")
mod_lm$results$RMSE  # Training RMSE
[1] 4.532099

1.3.1 Test RMSE

p <- predict(mod_lm, newdata = BostonTest_pp)
RMSE(BostonTest_pp$medv, p) # Test RMSE
[1] 4.525501

1.4 Linear model-Forward Selection

set.seed(123)
library(caret)
myControl <- trainControl(method = "cv", number = 5)
mod_fs <- train(medv ~ ., 
                data = BostonTrain_pp,
                trControl = myControl,
                method = "leapForward")
mod_fs$results$RMSE  # Training RMSE
[1] 5.504753 5.253257 5.037208
mod_fs
Linear Regression with Forward Selection 

381 samples
 13 predictor

No pre-processing
Resampling: Cross-Validated (5 fold) 
Summary of sample sizes: 306, 304, 304, 305, 305 
Resampling results across tuning parameters:

  nvmax  RMSE      Rsquared   MAE     
  2      5.504753  0.6664465  4.156683
  3      5.253257  0.6941767  3.878030
  4      5.037208  0.7174721  3.759551

RMSE was used to select the optimal model using the smallest value.
The final value used for the model was nvmax = 4.

1.4.1 Test RMSE

p <- predict(mod_fs, newdata = BostonTest_pp)
RMSE(BostonTest_pp$medv, p) # Test RMSE
[1] 4.570235

1.5 Linear model-Backward Elimination

set.seed(123)
library(caret)
myControl <- trainControl(method = "cv", number = 5)
mod_be <- train(medv ~ ., 
                data = BostonTrain_pp,
                trControl = myControl,
                method = "leapBackward")
mod_be$results$RMSE  # Training RMSE
[1] 5.419077 5.183117 4.923204
mod_be
Linear Regression with Backwards Selection 

381 samples
 13 predictor

No pre-processing
Resampling: Cross-Validated (5 fold) 
Summary of sample sizes: 306, 304, 304, 305, 305 
Resampling results across tuning parameters:

  nvmax  RMSE      Rsquared   MAE     
  2      5.419077  0.6765806  4.051136
  3      5.183117  0.7025103  3.802048
  4      4.923204  0.7306559  3.663932

RMSE was used to select the optimal model using the smallest value.
The final value used for the model was nvmax = 4.

1.5.1 Test RMSE

p <- predict(mod_be, newdata = BostonTest_pp)
RMSE(BostonTest_pp$medv, p) # Test RMSE
[1] 4.570235

1.6 Elasticnet

set.seed(123)
myControl <- trainControl(method = "cv", number = 5)
mod_glmnet <- train(medv ~ ., 
                data = BostonTrain_pp,
                trControl = myControl,
                method = "glmnet",
                tuneLength = 12)
Warning in nominalTrainWorkflow(x = x, y = y, wts = weights, info = trainInfo, :
There were missing values in resampled performance measures.
mod_glmnet
glmnet 

381 samples
 13 predictor

No pre-processing
Resampling: Cross-Validated (5 fold) 
Summary of sample sizes: 306, 304, 304, 305, 305 
Resampling results across tuning parameters:

  alpha      lambda       RMSE      Rsquared   MAE     
  0.1000000  0.006268536  4.532439  0.7687279  3.366651
  0.1000000  0.012730881  4.532439  0.7687279  3.366651
  0.1000000  0.025855371  4.532434  0.7687289  3.366623
  0.1000000  0.052510131  4.532340  0.7688297  3.359722
  0.1000000  0.106643752  4.535395  0.7687633  3.346245
  0.1000000  0.216584681  4.547595  0.7681490  3.325282
  0.1000000  0.439865657  4.589139  0.7654739  3.307271
  0.1000000  0.893330938  4.694705  0.7581140  3.320672
  0.1000000  1.814281591  4.914227  0.7423998  3.396554
  0.1000000  3.684656549  5.273332  0.7200617  3.587066
  0.1000000  7.483234110  5.829543  0.6977248  3.974399
  0.1818182  0.006268536  4.532654  0.7687016  3.368688
  0.1818182  0.012730881  4.532654  0.7687016  3.368688
  0.1818182  0.025855371  4.532432  0.7687406  3.367360
  0.1818182  0.052510131  4.533602  0.7687487  3.358871
  0.1818182  0.106643752  4.538685  0.7685477  3.344706
  0.1818182  0.216584681  4.556259  0.7675645  3.326035
  0.1818182  0.439865657  4.613467  0.7636242  3.318787
  0.1818182  0.893330938  4.752037  0.7533679  3.346220
  0.1818182  1.814281591  5.011448  0.7346916  3.470463
  0.1818182  3.684656549  5.429657  0.7095588  3.722030
  0.1818182  7.483234110  6.083102  0.7001301  4.189152
  0.2636364  0.006268536  4.532905  0.7686922  3.368850
  0.2636364  0.012730881  4.532905  0.7686922  3.368850
  0.2636364  0.025855371  4.532862  0.7687195  3.366632
  0.2636364  0.052510131  4.534693  0.7686882  3.357596
  0.2636364  0.106643752  4.541546  0.7683807  3.343626
  0.2636364  0.216584681  4.566515  0.7668266  3.328434
  0.2636364  0.439865657  4.637342  0.7618277  3.329551
  0.2636364  0.893330938  4.818059  0.7475144  3.387929
  0.2636364  1.814281591  5.100450  0.7274659  3.542196
  0.2636364  3.684656549  5.532147  0.7076851  3.821693
  0.2636364  7.483234110  6.344984  0.7034900  4.394777
  0.3454545  0.006268536  4.532998  0.7686950  3.368913
  0.3454545  0.012730881  4.532998  0.7686950  3.368913
  0.3454545  0.025855371  4.533374  0.7686898  3.366273
  0.3454545  0.052510131  4.536039  0.7686047  3.356808
  0.3454545  0.106643752  4.545000  0.7681604  3.343759
  0.3454545  0.216584681  4.577897  0.7659637  3.331930
  0.3454545  0.439865657  4.666327  0.7593644  3.341508
  0.3454545  0.893330938  4.880764  0.7419235  3.430270
  0.3454545  1.814281591  5.198336  0.7185241  3.619982
  0.3454545  3.684656549  5.638643  0.7059721  3.919628
  0.3454545  7.483234110  6.637428  0.6991054  4.628281
  0.4272727  0.006268536  4.533413  0.7686297  3.369439
  0.4272727  0.012730881  4.533413  0.7686297  3.369439
  0.4272727  0.025855371  4.533958  0.7686509  3.365646
  0.4272727  0.052510131  4.537495  0.7685109  3.355996
  0.4272727  0.106643752  4.549024  0.7678880  3.344393
  0.4272727  0.216584681  4.588161  0.7651822  3.333949
  0.4272727  0.439865657  4.701477  0.7562118  3.357889
  0.4272727  0.893330938  4.924674  0.7381924  3.465292
  0.4272727  1.814281591  5.282171  0.7107997  3.694325
  0.4272727  3.684656549  5.742911  0.7049116  4.009762
  0.4272727  7.483234110  6.948048  0.6873032  4.877146
  0.5090909  0.006268536  4.533625  0.7686237  3.369891
  0.5090909  0.012730881  4.533625  0.7686237  3.369891
  0.5090909  0.025855371  4.534373  0.7686321  3.365226
  0.5090909  0.052510131  4.538761  0.7684363  3.355401
  0.5090909  0.106643752  4.553503  0.7675701  3.345300
  0.5090909  0.216584681  4.598849  0.7643755  3.337297
  0.5090909  0.439865657  4.743445  0.7522809  3.379458
  0.5090909  0.893330938  4.964161  0.7348584  3.499293
  0.5090909  1.814281591  5.327524  0.7084565  3.744212
  0.5090909  3.684656549  5.859680  0.7022780  4.097255
  0.5090909  7.483234110  7.236792  0.6807820  5.094855
  0.5909091  0.006268536  4.533709  0.7686471  3.369558
  0.5909091  0.012730881  4.533703  0.7686489  3.369458
  0.5909091  0.025855371  4.534981  0.7685927  3.364541
  0.5909091  0.052510131  4.540154  0.7683524  3.354782
  0.5909091  0.106643752  4.558549  0.7671995  3.346364
  0.5909091  0.216584681  4.611191  0.7634038  3.341505
  0.5909091  0.439865657  4.778706  0.7490872  3.399497
  0.5909091  0.893330938  5.008661  0.7308346  3.541779
  0.5909091  1.814281591  5.368626  0.7069940  3.783998
  0.5909091  3.684656549  5.991761  0.6973993  4.201063
  0.5909091  7.483234110  7.552228  0.6710425  5.325813
  0.6727273  0.006268536  4.533560  0.7686403  3.370216
  0.6727273  0.012730881  4.533676  0.7686343  3.369678
  0.6727273  0.025855371  4.535553  0.7685605  3.363875
  0.6727273  0.052510131  4.541567  0.7682674  3.354559
  0.6727273  0.106643752  4.563678  0.7668108  3.347271
  0.6727273  0.216584681  4.625375  0.7621938  3.345673
  0.6727273  0.439865657  4.816237  0.7456108  3.423569
  0.6727273  0.893330938  5.057995  0.7261480  3.585362
  0.6727273  1.814281591  5.411921  0.7052613  3.820470
  0.6727273  3.684656549  6.139067  0.6892940  4.316349
  0.6727273  7.483234110  7.868986  0.6582170  5.568722
  0.7545455  0.006268536  4.533341  0.7686565  3.370423
  0.7545455  0.012730881  4.533745  0.7686322  3.369765
  0.7545455  0.025855371  4.536082  0.7685275  3.363364
  0.7545455  0.052510131  4.543215  0.7681604  3.354695
  0.7545455  0.106643752  4.568998  0.7663909  3.348084
  0.7545455  0.216584681  4.641303  0.7607902  3.351204
  0.7545455  0.439865657  4.849905  0.7424856  3.446269
  0.7545455  0.893330938  5.110714  0.7209550  3.628710
  0.7545455  1.814281591  5.456445  0.7033818  3.854451
  0.7545455  3.684656549  6.278055  0.6807482  4.422164
  0.7545455  7.483234110  8.168997  0.6551503  5.800493
  0.8363636  0.006268536  4.533531  0.7686379  3.370395
  0.8363636  0.012730881  4.534076  0.7686039  3.369372
  0.8363636  0.025855371  4.536829  0.7684784  3.362967
  0.8363636  0.052510131  4.544980  0.7680436  3.354808
  0.8363636  0.106643752  4.573321  0.7660719  3.347789
  0.8363636  0.216584681  4.659257  0.7591660  3.359311
  0.8363636  0.439865657  4.871195  0.7405887  3.464868
  0.8363636  0.893330938  5.159761  0.7161013  3.667872
  0.8363636  1.814281591  5.505150  0.7009574  3.889771
  0.8363636  3.684656549  6.405747  0.6751334  4.506194
  0.8363636  7.483234110  8.502518  0.6551503  6.061084
  0.9181818  0.006268536  4.533313  0.7686425  3.370200
  0.9181818  0.012730881  4.534173  0.7686003  3.369165
  0.9181818  0.025855371  4.537409  0.7684461  3.362507
  0.9181818  0.052510131  4.546884  0.7679146  3.354943
  0.9181818  0.106643752  4.577870  0.7657321  3.347478
  0.9181818  0.216584681  4.679381  0.7573027  3.368504
  0.9181818  0.439865657  4.888749  0.7390579  3.483665
  0.9181818  0.893330938  5.200906  0.7121487  3.698759
  0.9181818  1.814281591  5.559250  0.6978243  3.928229
  0.9181818  3.684656549  6.541536  0.6678327  4.594709
  0.9181818  7.483234110  8.888861  0.6551503  6.370009
  1.0000000  0.006268536  4.533643  0.7686382  3.371293
  1.0000000  0.012730881  4.534478  0.7685793  3.368978
  1.0000000  0.025855371  4.538183  0.7683940  3.362028
  1.0000000  0.052510131  4.548905  0.7677757  3.355140
  1.0000000  0.106643752  4.582861  0.7653509  3.347769
  1.0000000  0.216584681  4.702243  0.7551334  3.380174
  1.0000000  0.439865657  4.907375  0.7373982  3.503123
  1.0000000  0.893330938  5.233937  0.7091310  3.722923
  1.0000000  1.814281591  5.619076  0.6937479  3.972824
  1.0000000  3.684656549  6.674007  0.6602592  4.687782
  1.0000000  7.483234110  9.331357  0.6367301  6.725990

RMSE was used to select the optimal model using the smallest value.
The final values used for the model were alpha = 0.1 and lambda = 0.05251013.
min(mod_glmnet$results$RMSE)  # Training RMSE
[1] 4.53234
plot(mod_glmnet)

1.6.1 Test RMSE

p <- predict(mod_glmnet, newdata = BostonTest_pp)
RMSE(BostonTest_pp$medv, p) # Test RMSE
[1] 4.477451

1.6.1.1 LASSO

set.seed(123)
myControl <- trainControl(method = "cv", number = 5)
mod_lasso <- train(medv ~ ., 
                data = BostonTrain_pp,
                trControl = myControl,
                method = "glmnet",
                tuneGrid = expand.grid(alpha = 1, lambda = seq(.01, 2, length = 10))
)
mod_lasso
glmnet 

381 samples
 13 predictor

No pre-processing
Resampling: Cross-Validated (5 fold) 
Summary of sample sizes: 306, 304, 304, 305, 305 
Resampling results across tuning parameters:

  lambda     RMSE      Rsquared   MAE     
  0.0100000  4.533857  0.7686211  3.370604
  0.2311111  4.723225  0.7532066  3.389616
  0.4522222  4.915221  0.7367576  3.509206
  0.6733333  5.080905  0.7223991  3.628188
  0.8944444  5.234474  0.7090926  3.723285
  1.1155556  5.321999  0.7042096  3.786443
  1.3366667  5.403792  0.7014806  3.838754
  1.5577778  5.496363  0.6983004  3.895305
  1.7788889  5.601179  0.6944543  3.960799
  2.0000000  5.717715  0.6895725  4.046256

Tuning parameter 'alpha' was held constant at a value of 1
RMSE was used to select the optimal model using the smallest value.
The final values used for the model were alpha = 1 and lambda = 0.01.
min(mod_lasso$results$RMSE)  # Training RMSE
[1] 4.533857
plot(mod_lasso)

1.6.1.2 Test RMSE

p <- predict(mod_lasso, newdata = BostonTest_pp)
RMSE(BostonTest_pp$medv, p) # Test RMSE
[1] 4.50215

1.6.1.3 Ridge

set.seed(123)
myControl <- trainControl(method = "cv", number = 5)
mod_ridge <- train(medv ~ ., 
                data = BostonTrain_pp,
                trControl = myControl,
                method = "glmnet",
                tuneGrid = expand.grid(alpha = 0, lambda = seq(.01, 2, length = 10))
)
mod_ridge
glmnet 

381 samples
 13 predictor

No pre-processing
Resampling: Cross-Validated (5 fold) 
Summary of sample sizes: 306, 304, 304, 305, 305 
Resampling results across tuning parameters:

  lambda     RMSE      Rsquared   MAE     
  0.0100000  4.614966  0.7636989  3.294877
  0.2311111  4.614966  0.7636989  3.294877
  0.4522222  4.614966  0.7636989  3.294877
  0.6733333  4.614966  0.7636989  3.294877
  0.8944444  4.638327  0.7621104  3.297334
  1.1155556  4.676050  0.7595030  3.302091
  1.3366667  4.713953  0.7568811  3.308025
  1.5577778  4.751331  0.7543100  3.314761
  1.7788889  4.787935  0.7518072  3.322928
  2.0000000  4.823847  0.7493672  3.332524

Tuning parameter 'alpha' was held constant at a value of 0
RMSE was used to select the optimal model using the smallest value.
The final values used for the model were alpha = 0 and lambda = 0.6733333.
min(mod_ridge$results$RMSE)  # Training RMSE
[1] 4.614966
plot(mod_ridge)

1.6.1.4 Test RMSE

p <- predict(mod_ridge, newdata = BostonTest_pp)
RMSE(BostonTest_pp$medv, p) # Test RMSE
[1] 4.203053

1.7 Recursive Partitioning (Trees)

library(rpart)
mod_tree <- rpart(medv ~., data = BostonTrain_pp)
mod_tree
n= 381 

node), split, n, deviance, yval
      * denotes terminal node

 1) root 381 33992.1300 22.71365  
   2) rm< 0.9537213 330 14327.9400 20.14727  
     4) lstat>=0.4346317 134  2458.8170 15.11567  
       8) nox>=0.6116656 83   995.7316 13.03614  
        16) lstat>=0.9553247 45   324.6720 10.91333 *
        17) lstat< 0.9553247 38   228.1350 15.55000 *
       9) nox< 0.6116656 51   520.0200 18.50000 *
     5) lstat< 0.4346317 196  6157.2980 23.58724  
      10) lstat>=-1.192108 178  3600.5860 22.67584  
        20) lstat>=-0.2367871 85   435.8631 20.72588 *
        21) lstat< -0.2367871 93  2546.1260 24.45806  
          42) age< 0.7414282 86  1086.6980 23.69535 *
          43) age>=0.7414282 7   794.7543 33.82857 *
      11) lstat< -1.192108 18   946.7200 32.60000 *
   3) rm>=0.9537213 51  3427.0600 39.31961  
     6) rm< 1.538942 24   736.3200 33.30000 *
     7) rm>=1.538942 27  1048.0560 44.67037 *
library(partykit)
Loading required package: grid
Loading required package: libcoin
Loading required package: mvtnorm
plot(as.party(mod_tree))

rpart.plot::rpart.plot(mod_tree)

set.seed(123)
mod_TR <- train(medv ~ ., 
                data = BostonTrain_pp,
                trControl = myControl,
                method = "rpart",
                tuneLength = 10)
Warning in nominalTrainWorkflow(x = x, y = y, wts = weights, info = trainInfo, :
There were missing values in resampled performance measures.
mod_TR$bestTune
           cp
1 0.003136858
mod_TR2 <- rpart(medv ~.,
                 data = BostonTrain_pp,
                 cp = mod_TR$bestTune)
rpart.plot::rpart.plot(mod_TR2)

mod_TR2
n= 381 

node), split, n, deviance, yval
      * denotes terminal node

 1) root 381 33992.1300 22.71365  
   2) rm< 0.9537213 330 14327.9400 20.14727  
     4) lstat>=0.4346317 134  2458.8170 15.11567  
       8) nox>=0.6116656 83   995.7316 13.03614  
        16) lstat>=0.9553247 45   324.6720 10.91333 *
        17) lstat< 0.9553247 38   228.1350 15.55000 *
       9) nox< 0.6116656 51   520.0200 18.50000 *
     5) lstat< 0.4346317 196  6157.2980 23.58724  
      10) lstat>=-1.192108 178  3600.5860 22.67584  
        20) lstat>=-0.2367871 85   435.8631 20.72588 *
        21) lstat< -0.2367871 93  2546.1260 24.45806  
          42) age< 0.7414282 86  1086.6980 23.69535  
            84) rm< -0.1881725 25   168.9616 20.64400 *
            85) rm>=-0.1881725 61   589.5715 24.94590 *
          43) age>=0.7414282 7   794.7543 33.82857 *
      11) lstat< -1.192108 18   946.7200 32.60000 *
   3) rm>=0.9537213 51  3427.0600 39.31961  
     6) rm< 1.538942 24   736.3200 33.30000 *
     7) rm>=1.538942 27  1048.0560 44.67037  
      14) ptratio>=-0.4488431 7   465.9686 38.88571 *
      15) ptratio< -0.4488431 20   265.8695 46.69500 *

1.7.0.1 Test RMSE

p <- predict(mod_TR2, newdata = BostonTest_pp)
RMSE(BostonTest_pp$medv, p) # Test RMSE
[1] 4.352689

1.8 Bagging

set.seed(123)
myControl <- trainControl(method = "cv", number = 5)
mod_tb <- train(medv ~ ., 
                data = BostonTrain_pp,
                trControl = myControl,
                method = "treebag"
                )
mod_tb
Bagged CART 

381 samples
 13 predictor

No pre-processing
Resampling: Cross-Validated (5 fold) 
Summary of sample sizes: 306, 304, 304, 305, 305 
Resampling results:

  RMSE      Rsquared   MAE    
  4.276616  0.8018699  2.85511
min(mod_tb$results$RMSE)  # Training RMSE
[1] 4.276616

1.8.1 Test RMSE

p <- predict(mod_tb, newdata = BostonTest_pp)
RMSE(BostonTest_pp$medv, p) # Test RMSE
[1] 3.557732

1.9 Random Forest

set.seed(123)
myControl <- trainControl(method = "cv", number = 5)
mod_rf <- train(medv ~ ., 
                data = BostonTrain_pp,
                trControl = myControl,
                method = "ranger",
                tuneLength = 12)
mod_rf
Random Forest 

381 samples
 13 predictor

No pre-processing
Resampling: Cross-Validated (5 fold) 
Summary of sample sizes: 306, 304, 304, 305, 305 
Resampling results across tuning parameters:

  mtry  splitrule   RMSE      Rsquared   MAE     
   2    variance    3.832880  0.8587448  2.518141
   2    extratrees  4.377025  0.8255921  2.874423
   3    variance    3.566681  0.8729650  2.347728
   3    extratrees  3.916764  0.8552296  2.587714
   4    variance    3.522161  0.8710633  2.338540
   4    extratrees  3.754917  0.8644915  2.482833
   5    variance    3.436735  0.8758546  2.274182
   5    extratrees  3.640429  0.8698941  2.419017
   6    variance    3.430548  0.8745581  2.278716
   6    extratrees  3.562520  0.8728870  2.381780
   7    variance    3.417798  0.8739443  2.275479
   7    extratrees  3.510473  0.8747282  2.350010
   8    variance    3.428135  0.8732117  2.282252
   8    extratrees  3.487387  0.8758874  2.336196
   9    variance    3.400881  0.8737789  2.291316
   9    extratrees  3.491114  0.8740669  2.352886
  10    variance    3.402442  0.8735321  2.286201
  10    extratrees  3.450158  0.8759239  2.324320
  11    variance    3.429615  0.8708211  2.309345
  11    extratrees  3.452930  0.8752728  2.331822
  12    variance    3.410061  0.8719447  2.321055
  12    extratrees  3.496607  0.8715495  2.362804
  13    variance    3.407644  0.8721424  2.313051
  13    extratrees  3.425564  0.8760149  2.306613

Tuning parameter 'min.node.size' was held constant at a value of 5
RMSE was used to select the optimal model using the smallest value.
The final values used for the model were mtry = 9, splitrule = variance
 and min.node.size = 5.
min(mod_rf$results$RMSE)  # Training RMSE
[1] 3.400881
plot(mod_rf)

1.9.1 Test RMSE

p <- predict(mod_rf, newdata = BostonTest_pp)
RMSE(BostonTest_pp$medv, p) # Test RMSE
[1] 3.102119

1.10 Gradient Boosting

set.seed(123)
myControl <- trainControl(method = "cv", number = 5)
mod_gbm <- train(medv ~ ., 
                data = BostonTrain_pp,
                trControl = myControl,
                method = "gbm",
                tuneLength = 20)
Iter   TrainDeviance   ValidDeviance   StepSize   Improve
     1       75.6884            -nan     0.1000   14.2046
     2       64.4558            -nan     0.1000    9.3659
     3       55.6707            -nan     0.1000    8.2594
     4       47.9617            -nan     0.1000    7.3983
     5       42.5233            -nan     0.1000    5.2637
     6       36.7843            -nan     0.1000    4.4107
     7       32.2402            -nan     0.1000    3.8943
     8       28.4577            -nan     0.1000    3.9754
     9       25.6642            -nan     0.1000    2.2407
    10       23.3743            -nan     0.1000    2.2380
    20       11.2762            -nan     0.1000    0.5320
    40        6.6221            -nan     0.1000   -0.0161
    60        5.0413            -nan     0.1000   -0.0364
    80        3.9552            -nan     0.1000   -0.0087
   100        3.2304            -nan     0.1000   -0.0508
   120        2.6122            -nan     0.1000   -0.0267
   140        2.1447            -nan     0.1000   -0.0429
   160        1.7561            -nan     0.1000   -0.0187
   180        1.5514            -nan     0.1000   -0.0289
   200        1.3145            -nan     0.1000   -0.0384
mod_gbm
Stochastic Gradient Boosting 

381 samples
 13 predictor

No pre-processing
Resampling: Cross-Validated (5 fold) 
Summary of sample sizes: 306, 304, 304, 305, 305 
Resampling results across tuning parameters:

  interaction.depth  n.trees  RMSE      Rsquared   MAE     
   1                   50     4.451152  0.7864359  3.011257
   1                  100     4.109568  0.8138500  2.775736
   1                  150     3.929309  0.8298694  2.680151
   1                  200     3.832390  0.8367381  2.627192
   1                  250     3.773408  0.8424542  2.608625
   1                  300     3.713891  0.8462146  2.587394
   1                  350     3.694013  0.8478988  2.584969
   1                  400     3.691708  0.8486147  2.596579
   1                  450     3.677633  0.8493879  2.582316
   1                  500     3.695428  0.8477856  2.596395
   1                  550     3.706509  0.8467550  2.588017
   1                  600     3.706668  0.8468436  2.604690
   1                  650     3.695580  0.8472985  2.602236
   1                  700     3.692024  0.8478357  2.600929
   1                  750     3.691078  0.8478392  2.600378
   1                  800     3.694967  0.8477300  2.618990
   1                  850     3.703207  0.8471694  2.618328
   1                  900     3.707360  0.8460017  2.632847
   1                  950     3.700380  0.8469821  2.638779
   1                 1000     3.716516  0.8453866  2.650945
   2                   50     3.968495  0.8268408  2.657663
   2                  100     3.709946  0.8469872  2.508794
   2                  150     3.580199  0.8576971  2.453141
   2                  200     3.517004  0.8621985  2.437679
   2                  250     3.509548  0.8626281  2.411141
   2                  300     3.459232  0.8666147  2.385462
   2                  350     3.461048  0.8669143  2.373748
   2                  400     3.454198  0.8675886  2.390997
   2                  450     3.473485  0.8664676  2.411977
   2                  500     3.479975  0.8663723  2.420820
   2                  550     3.500562  0.8648682  2.448401
   2                  600     3.488901  0.8657505  2.426532
   2                  650     3.492164  0.8653689  2.433405
   2                  700     3.485283  0.8658658  2.430141
   2                  750     3.494319  0.8653589  2.443872
   2                  800     3.506938  0.8643381  2.452926
   2                  850     3.513508  0.8637381  2.466779
   2                  900     3.501116  0.8643771  2.464208
   2                  950     3.517297  0.8633424  2.461583
   2                 1000     3.503417  0.8641769  2.464591
   3                   50     3.700042  0.8491692  2.461813
   3                  100     3.479851  0.8646017  2.347374
   3                  150     3.372917  0.8736233  2.285919
   3                  200     3.352719  0.8743431  2.287300
   3                  250     3.323706  0.8769912  2.259408
   3                  300     3.312354  0.8775965  2.262779
   3                  350     3.351715  0.8749933  2.299495
   3                  400     3.308819  0.8781178  2.291817
   3                  450     3.317245  0.8777984  2.286113
   3                  500     3.319482  0.8774039  2.288868
   3                  550     3.324284  0.8770846  2.286412
   3                  600     3.321331  0.8771627  2.294854
   3                  650     3.320443  0.8773447  2.286381
   3                  700     3.323092  0.8773616  2.286139
   3                  750     3.338928  0.8762207  2.295631
   3                  800     3.338174  0.8760089  2.291177
   3                  850     3.333413  0.8763985  2.293207
   3                  900     3.333496  0.8764428  2.290923
   3                  950     3.340453  0.8758718  2.298565
   3                 1000     3.344721  0.8754742  2.305501
   4                   50     3.635411  0.8529060  2.379303
   4                  100     3.410958  0.8712131  2.288640
   4                  150     3.349862  0.8747448  2.273745
   4                  200     3.359076  0.8745910  2.304713
   4                  250     3.326679  0.8771685  2.270224
   4                  300     3.340439  0.8767908  2.290605
   4                  350     3.371555  0.8743083  2.318847
   4                  400     3.368932  0.8743994  2.319685
   4                  450     3.390784  0.8729003  2.328889
   4                  500     3.392564  0.8726008  2.321965
   4                  550     3.404524  0.8716178  2.326176
   4                  600     3.415021  0.8709230  2.338148
   4                  650     3.422479  0.8702395  2.350211
   4                  700     3.418773  0.8704117  2.347827
   4                  750     3.427829  0.8695599  2.354638
   4                  800     3.435631  0.8688879  2.357233
   4                  850     3.442011  0.8684789  2.359286
   4                  900     3.439029  0.8687072  2.361057
   4                  950     3.438445  0.8687354  2.363285
   4                 1000     3.441250  0.8685503  2.366076
   5                   50     3.687599  0.8497471  2.424253
   5                  100     3.461143  0.8666927  2.350173
   5                  150     3.419019  0.8697179  2.343277
   5                  200     3.421563  0.8691593  2.349777
   5                  250     3.425595  0.8690723  2.341879
   5                  300     3.446546  0.8680009  2.359538
   5                  350     3.454453  0.8676852  2.360944
   5                  400     3.463285  0.8672009  2.369296
   5                  450     3.472229  0.8667449  2.383037
   5                  500     3.470724  0.8665423  2.378817
   5                  550     3.487875  0.8653935  2.397105
   5                  600     3.496351  0.8645940  2.408957
   5                  650     3.495991  0.8646606  2.413306
   5                  700     3.501778  0.8643184  2.419154
   5                  750     3.506894  0.8640021  2.426643
   5                  800     3.507234  0.8638896  2.429748
   5                  850     3.512331  0.8634990  2.430840
   5                  900     3.518025  0.8631704  2.434838
   5                  950     3.521682  0.8629261  2.436378
   5                 1000     3.520685  0.8629195  2.437084
   6                   50     3.562727  0.8621188  2.373177
   6                  100     3.414576  0.8725981  2.286023
   6                  150     3.354404  0.8761831  2.246834
   6                  200     3.358960  0.8755248  2.243536
   6                  250     3.362844  0.8748492  2.263744
   6                  300     3.334375  0.8766991  2.251438
   6                  350     3.335976  0.8767340  2.252848
   6                  400     3.346424  0.8761219  2.258466
   6                  450     3.348191  0.8759715  2.264076
   6                  500     3.359655  0.8750895  2.273217
   6                  550     3.353388  0.8755587  2.277752
   6                  600     3.361009  0.8751118  2.280557
   6                  650     3.364715  0.8748335  2.286891
   6                  700     3.370369  0.8744029  2.292485
   6                  750     3.373019  0.8742177  2.295420
   6                  800     3.365999  0.8746529  2.291531
   6                  850     3.371152  0.8742445  2.296489
   6                  900     3.369039  0.8744371  2.297784
   6                  950     3.373315  0.8740674  2.301897
   6                 1000     3.374367  0.8740068  2.304299
   7                   50     3.600198  0.8576736  2.343472
   7                  100     3.349264  0.8737095  2.219034
   7                  150     3.299229  0.8774078  2.215100
   7                  200     3.319528  0.8766071  2.242905
   7                  250     3.339707  0.8750852  2.276962
   7                  300     3.339280  0.8754424  2.282841
   7                  350     3.352456  0.8748033  2.299925
   7                  400     3.372470  0.8730936  2.316286
   7                  450     3.399131  0.8712555  2.332561
   7                  500     3.393273  0.8719018  2.340039
   7                  550     3.399609  0.8713487  2.342887
   7                  600     3.410639  0.8706000  2.350960
   7                  650     3.419303  0.8699738  2.359089
   7                  700     3.420250  0.8697987  2.358479
   7                  750     3.423921  0.8696274  2.360539
   7                  800     3.424717  0.8695570  2.359914
   7                  850     3.422903  0.8697490  2.358896
   7                  900     3.426555  0.8694682  2.363363
   7                  950     3.425600  0.8694990  2.362359
   7                 1000     3.424421  0.8695982  2.362550
   8                   50     3.534142  0.8629654  2.313172
   8                  100     3.358545  0.8741616  2.227429
   8                  150     3.305382  0.8788410  2.210188
   8                  200     3.266058  0.8817258  2.197039
   8                  250     3.276128  0.8807114  2.209759
   8                  300     3.291441  0.8794441  2.227556
   8                  350     3.314448  0.8779046  2.236977
   8                  400     3.326401  0.8773032  2.245626
   8                  450     3.324268  0.8774341  2.246092
   8                  500     3.326766  0.8772570  2.256470
   8                  550     3.326936  0.8772732  2.258736
   8                  600     3.332522  0.8768278  2.262946
   8                  650     3.334025  0.8766931  2.265762
   8                  700     3.342805  0.8760700  2.270930
   8                  750     3.346872  0.8757576  2.273352
   8                  800     3.346667  0.8757818  2.271745
   8                  850     3.347435  0.8756806  2.275168
   8                  900     3.349427  0.8755582  2.276192
   8                  950     3.348645  0.8755895  2.275491
   8                 1000     3.350099  0.8754895  2.277826
   9                   50     3.600223  0.8566141  2.335488
   9                  100     3.397071  0.8711413  2.263157
   9                  150     3.326430  0.8757905  2.234868
   9                  200     3.335975  0.8752120  2.256410
   9                  250     3.341405  0.8746543  2.255798
   9                  300     3.340177  0.8750335  2.273833
   9                  350     3.361233  0.8734328  2.288459
   9                  400     3.375981  0.8728186  2.297401
   9                  450     3.380010  0.8726227  2.304728
   9                  500     3.386854  0.8722360  2.311340
   9                  550     3.394522  0.8716256  2.321909
   9                  600     3.400188  0.8712078  2.327830
   9                  650     3.394535  0.8717505  2.327926
   9                  700     3.400401  0.8712486  2.329972
   9                  750     3.404834  0.8709282  2.333258
   9                  800     3.403585  0.8710867  2.332798
   9                  850     3.410977  0.8705410  2.338042
   9                  900     3.412692  0.8704537  2.339550
   9                  950     3.423312  0.8696768  2.344603
   9                 1000     3.423576  0.8696229  2.345321
  10                   50     3.551660  0.8594353  2.344162
  10                  100     3.377726  0.8723291  2.261835
  10                  150     3.350703  0.8739261  2.256344
  10                  200     3.364239  0.8733467  2.271046
  10                  250     3.353075  0.8744479  2.277147
  10                  300     3.369293  0.8736188  2.291680
  10                  350     3.362223  0.8740732  2.285120
  10                  400     3.370423  0.8735461  2.292665
  10                  450     3.381252  0.8728576  2.302221
  10                  500     3.376267  0.8733703  2.296071
  10                  550     3.387489  0.8725058  2.305201
  10                  600     3.383516  0.8727469  2.308350
  10                  650     3.379627  0.8731621  2.305435
  10                  700     3.379353  0.8731049  2.306646
  10                  750     3.380698  0.8730749  2.307528
  10                  800     3.381078  0.8730169  2.306320
  10                  850     3.379267  0.8731464  2.306739
  10                  900     3.379993  0.8730474  2.307428
  10                  950     3.378785  0.8731574  2.309110
  10                 1000     3.380822  0.8729767  2.309700
  11                   50     3.476049  0.8656434  2.270222
  11                  100     3.298553  0.8780055  2.217835
  11                  150     3.284762  0.8790490  2.208018
  11                  200     3.284178  0.8795091  2.218634
  11                  250     3.304236  0.8782755  2.240085
  11                  300     3.321624  0.8768016  2.245713
  11                  350     3.332550  0.8764151  2.258416
  11                  400     3.321305  0.8771209  2.253855
  11                  450     3.328842  0.8767080  2.261085
  11                  500     3.337383  0.8761716  2.266228
  11                  550     3.336043  0.8763889  2.267463
  11                  600     3.333611  0.8765204  2.265961
  11                  650     3.337522  0.8761347  2.271666
  11                  700     3.331421  0.8765714  2.269293
  11                  750     3.337736  0.8761556  2.271913
  11                  800     3.338369  0.8761320  2.270479
  11                  850     3.339400  0.8760438  2.270568
  11                  900     3.341383  0.8758189  2.271146
  11                  950     3.342022  0.8757744  2.271929
  11                 1000     3.343100  0.8756254  2.272402
  12                   50     3.500355  0.8656684  2.370335
  12                  100     3.377388  0.8721419  2.281756
  12                  150     3.373376  0.8722776  2.266652
  12                  200     3.349516  0.8735682  2.232636
  12                  250     3.375206  0.8721383  2.245746
  12                  300     3.399947  0.8702676  2.268464
  12                  350     3.396986  0.8705661  2.269501
  12                  400     3.409390  0.8697219  2.273315
  12                  450     3.416081  0.8692231  2.279094
  12                  500     3.421686  0.8689740  2.282378
  12                  550     3.424757  0.8687100  2.289025
  12                  600     3.428155  0.8685507  2.289822
  12                  650     3.428401  0.8684944  2.297986
  12                  700     3.430481  0.8683887  2.298142
  12                  750     3.435349  0.8680165  2.306155
  12                  800     3.434624  0.8680937  2.306660
  12                  850     3.436419  0.8679792  2.307227
  12                  900     3.440406  0.8676355  2.311556
  12                  950     3.438874  0.8677666  2.310788
  12                 1000     3.438040  0.8678436  2.309864
  13                   50     3.573538  0.8575720  2.372747
  13                  100     3.398453  0.8694819  2.285241
  13                  150     3.396545  0.8697495  2.301357
  13                  200     3.394866  0.8699206  2.313971
  13                  250     3.381338  0.8709699  2.304600
  13                  300     3.414767  0.8684344  2.332100
  13                  350     3.422011  0.8681369  2.333000
  13                  400     3.423114  0.8680437  2.329125
  13                  450     3.423142  0.8680437  2.331525
  13                  500     3.431193  0.8675941  2.340223
  13                  550     3.435995  0.8673378  2.337968
  13                  600     3.444249  0.8667302  2.341254
  13                  650     3.449477  0.8663039  2.343634
  13                  700     3.453883  0.8659716  2.349377
  13                  750     3.454523  0.8658908  2.349951
  13                  800     3.454474  0.8658835  2.352056
  13                  850     3.455746  0.8658216  2.353103
  13                  900     3.458408  0.8655870  2.355712
  13                  950     3.457647  0.8656278  2.356097
  13                 1000     3.458746  0.8655097  2.357813
  14                   50     3.509508  0.8645793  2.326039
  14                  100     3.400867  0.8717357  2.278107
  14                  150     3.357513  0.8751319  2.248063
  14                  200     3.354450  0.8752147  2.246719
  14                  250     3.358252  0.8753362  2.241946
  14                  300     3.357438  0.8755660  2.240811
  14                  350     3.358342  0.8756358  2.238202
  14                  400     3.366128  0.8751656  2.245917
  14                  450     3.377133  0.8745649  2.250316
  14                  500     3.370458  0.8750783  2.258345
  14                  550     3.377885  0.8745672  2.259154
  14                  600     3.385521  0.8741311  2.262224
  14                  650     3.384801  0.8742464  2.265606
  14                  700     3.381897  0.8745283  2.269435
  14                  750     3.383198  0.8744353  2.268528
  14                  800     3.383080  0.8744069  2.266507
  14                  850     3.383820  0.8743805  2.268870
  14                  900     3.385582  0.8741716  2.271275
  14                  950     3.385360  0.8741634  2.272109
  14                 1000     3.383724  0.8742791  2.271739
  15                   50     3.524443  0.8625236  2.344654
  15                  100     3.478066  0.8653876  2.330499
  15                  150     3.440958  0.8682866  2.317318
  15                  200     3.436551  0.8687245  2.338543
  15                  250     3.454775  0.8676263  2.348942
  15                  300     3.463345  0.8670830  2.358125
  15                  350     3.465113  0.8671021  2.371358
  15                  400     3.471281  0.8667889  2.365160
  15                  450     3.481736  0.8661798  2.382107
  15                  500     3.489374  0.8657879  2.394309
  15                  550     3.486224  0.8659965  2.392553
  15                  600     3.489722  0.8657916  2.398088
  15                  650     3.498798  0.8652350  2.406346
  15                  700     3.500283  0.8650770  2.411243
  15                  750     3.501835  0.8649572  2.411949
  15                  800     3.502010  0.8649565  2.415881
  15                  850     3.504662  0.8647291  2.419911
  15                  900     3.504603  0.8647080  2.420116
  15                  950     3.508592  0.8644492  2.421693
  15                 1000     3.510185  0.8643706  2.424943
  16                   50     3.480292  0.8661379  2.364637
  16                  100     3.351235  0.8743604  2.329051
  16                  150     3.316853  0.8776898  2.305955
  16                  200     3.285044  0.8792062  2.293189
  16                  250     3.268554  0.8806654  2.277981
  16                  300     3.277325  0.8801980  2.300204
  16                  350     3.296195  0.8793428  2.313751
  16                  400     3.279332  0.8803660  2.297134
  16                  450     3.289713  0.8797768  2.300444
  16                  500     3.295215  0.8794980  2.306330
  16                  550     3.306169  0.8786862  2.310016
  16                  600     3.304311  0.8787948  2.308780
  16                  650     3.309007  0.8785331  2.312359
  16                  700     3.310203  0.8783484  2.315911
  16                  750     3.313151  0.8781876  2.321599
  16                  800     3.309144  0.8784136  2.315027
  16                  850     3.313548  0.8781647  2.318762
  16                  900     3.313304  0.8782184  2.317921
  16                  950     3.313595  0.8781890  2.316081
  16                 1000     3.311923  0.8783148  2.316118
  17                   50     3.521837  0.8635578  2.312638
  17                  100     3.396253  0.8705684  2.235455
  17                  150     3.389813  0.8708138  2.241884
  17                  200     3.400687  0.8703217  2.253133
  17                  250     3.409662  0.8703477  2.260618
  17                  300     3.411331  0.8704195  2.267147
  17                  350     3.424817  0.8697822  2.271564
  17                  400     3.436516  0.8690917  2.281009
  17                  450     3.432944  0.8694749  2.282822
  17                  500     3.447470  0.8686245  2.291879
  17                  550     3.443714  0.8689127  2.293932
  17                  600     3.445267  0.8687809  2.291964
  17                  650     3.450222  0.8683127  2.297226
  17                  700     3.453113  0.8681731  2.297534
  17                  750     3.457776  0.8678932  2.302505
  17                  800     3.461964  0.8676046  2.306283
  17                  850     3.459864  0.8678212  2.303313
  17                  900     3.459815  0.8677994  2.305933
  17                  950     3.459692  0.8678309  2.306816
  17                 1000     3.461647  0.8676895  2.307294
  18                   50     3.475133  0.8652138  2.279452
  18                  100     3.318117  0.8777758  2.233119
  18                  150     3.343652  0.8749120  2.244967
  18                  200     3.326673  0.8762044  2.222860
  18                  250     3.355968  0.8741937  2.242153
  18                  300     3.351920  0.8748511  2.259469
  18                  350     3.367729  0.8736944  2.263664
  18                  400     3.375179  0.8731673  2.267943
  18                  450     3.367465  0.8737756  2.269143
  18                  500     3.387731  0.8722778  2.279568
  18                  550     3.390345  0.8721510  2.284280
  18                  600     3.388465  0.8722423  2.286331
  18                  650     3.393304  0.8718478  2.289949
  18                  700     3.396631  0.8716770  2.291170
  18                  750     3.399299  0.8714660  2.293965
  18                  800     3.404287  0.8711195  2.299957
  18                  850     3.403829  0.8711300  2.303157
  18                  900     3.406843  0.8709117  2.304503
  18                  950     3.408037  0.8709299  2.307370
  18                 1000     3.408288  0.8708678  2.307114
  19                   50     3.507833  0.8626627  2.330554
  19                  100     3.325693  0.8759116  2.233233
  19                  150     3.275151  0.8792075  2.206423
  19                  200     3.298094  0.8777064  2.215961
  19                  250     3.307466  0.8776320  2.206130
  19                  300     3.323675  0.8766334  2.210116
  19                  350     3.333471  0.8759270  2.212928
  19                  400     3.337530  0.8756816  2.222182
  19                  450     3.349797  0.8747741  2.228137
  19                  500     3.344613  0.8751162  2.233170
  19                  550     3.350803  0.8747210  2.242486
  19                  600     3.358832  0.8740604  2.243485
  19                  650     3.365364  0.8735821  2.251019
  19                  700     3.366706  0.8734248  2.253833
  19                  750     3.368545  0.8733049  2.255918
  19                  800     3.369470  0.8732248  2.256726
  19                  850     3.368225  0.8733395  2.255602
  19                  900     3.367437  0.8734098  2.256305
  19                  950     3.371530  0.8731676  2.257948
  19                 1000     3.372622  0.8730043  2.259411
  20                   50     3.568770  0.8583578  2.354901
  20                  100     3.424282  0.8682108  2.275533
  20                  150     3.348994  0.8737787  2.242433
  20                  200     3.352860  0.8739379  2.237980
  20                  250     3.351720  0.8741891  2.243985
  20                  300     3.361999  0.8734664  2.251741
  20                  350     3.354823  0.8743319  2.247359
  20                  400     3.356180  0.8745392  2.254295
  20                  450     3.358151  0.8743574  2.258660
  20                  500     3.362153  0.8741687  2.262248
  20                  550     3.369574  0.8736024  2.266376
  20                  600     3.374862  0.8731966  2.272978
  20                  650     3.378412  0.8729433  2.275386
  20                  700     3.379784  0.8727832  2.278675
  20                  750     3.379932  0.8728234  2.280194
  20                  800     3.379132  0.8729065  2.282742
  20                  850     3.380461  0.8727394  2.282683
  20                  900     3.379012  0.8728288  2.284638
  20                  950     3.379408  0.8727467  2.284248
  20                 1000     3.380292  0.8726943  2.284023

Tuning parameter 'shrinkage' was held constant at a value of 0.1

Tuning parameter 'n.minobsinnode' was held constant at a value of 10
RMSE was used to select the optimal model using the smallest value.
The final values used for the model were n.trees = 200, interaction.depth =
 8, shrinkage = 0.1 and n.minobsinnode = 10.
min(mod_gbm$results$RMSE)  # Training RMSE
[1] 3.266058
plot(mod_gbm)

1.10.1 Test RMSE

p <- predict(mod_gbm, newdata = BostonTest_pp)
RMSE(BostonTest_pp$medv, p) # Test RMSE
[1] 3.007369

1.11 Support Vector Machines

set.seed(123)
myControl <- trainControl(method = "cv", number = 5)
mod_svm <- train(medv ~ ., 
                data = BostonTrain_pp,
                trControl = myControl,
                method = "svmRadial",
                tuneLength = 12)
mod_svm
Support Vector Machines with Radial Basis Function Kernel 

381 samples
 13 predictor

No pre-processing
Resampling: Cross-Validated (5 fold) 
Summary of sample sizes: 306, 304, 304, 305, 305 
Resampling results across tuning parameters:

  C       RMSE      Rsquared   MAE     
    0.25  5.130914  0.7486183  3.002551
    0.50  4.610427  0.7876803  2.736412
    1.00  4.126431  0.8235969  2.558077
    2.00  3.714840  0.8531095  2.374209
    4.00  3.614707  0.8558090  2.310476
    8.00  3.574915  0.8586898  2.306565
   16.00  3.553400  0.8590206  2.338155
   32.00  3.597014  0.8534230  2.414552
   64.00  3.736243  0.8411513  2.522262
  128.00  3.863299  0.8308018  2.588757
  256.00  4.041082  0.8171449  2.668202
  512.00  4.113218  0.8108560  2.693553

Tuning parameter 'sigma' was held constant at a value of 0.0884089
RMSE was used to select the optimal model using the smallest value.
The final values used for the model were sigma = 0.0884089 and C = 16.
min(mod_svm$results$RMSE)  # Training RMSE
[1] 3.5534
plot(mod_svm)

1.11.1 Test RMSE

p <- predict(mod_svm, newdata = BostonTest_pp)
RMSE(BostonTest_pp$medv, p) # Test RMSE
[1] 2.721747

1.12 k-nearest neighbors

set.seed(123)
myControl <- trainControl(method = "cv", number = 5)
mod_knn <- train(medv ~ ., 
                data = BostonTrain_pp,
                trControl = myControl,
                method = "knn",
                tuneLength = 12)
mod_knn
k-Nearest Neighbors 

381 samples
 13 predictor

No pre-processing
Resampling: Cross-Validated (5 fold) 
Summary of sample sizes: 306, 304, 304, 305, 305 
Resampling results across tuning parameters:

  k   RMSE      Rsquared   MAE     
   5  5.127388  0.7090687  3.178419
   7  4.956041  0.7354359  3.147579
   9  4.993595  0.7411511  3.164132
  11  5.145678  0.7311013  3.236609
  13  5.231936  0.7262360  3.248706
  15  5.229716  0.7291167  3.243414
  17  5.367630  0.7169652  3.337101
  19  5.471290  0.7066006  3.395800
  21  5.558299  0.7008257  3.464050
  23  5.655375  0.6945242  3.536193
  25  5.748517  0.6870365  3.585939
  27  5.797428  0.6847486  3.619724

RMSE was used to select the optimal model using the smallest value.
The final value used for the model was k = 7.
min(mod_knn$results$RMSE)  # Training RMSE
[1] 4.956041
plot(mod_knn)

1.12.1 Test RMSE

p <- predict(mod_knn, newdata = BostonTest_pp)
RMSE(BostonTest_pp$medv, p) # Test RMSE
[1] 3.48389