K-Fold Cross Validation.R

# ---------------------------------------------------- Importing Data ----------------------------------------- #

dataset = read.csv('Social_Network_Ad.csv')

# Selecting particular columns
dataset = dataset[3:5]

# ---------------------------------------- Encoding the target feature as factor ------------------------------ #

dataset$Purchased = factor(dataset$Purchased, levels = c(0, 1))

# ---------------------------------- Splitting the dataset into Training and Test Set ------------------------- #

# install.packages('caTools')
library(caTools)
set.seed(123)
split = sample.split(dataset$Purchased, SplitRatio = 0.75)
training_set = subset(dataset, split == TRUE)
test_set = subset(dataset, split == FALSE)

# --------------------------------------------------- Feature Scalling ----------------------------------------- #

training_set[-3] = scale(training_set[-3])
test_set[-3] = scale(test_set[-3])

# ---------------------------------------- Fitting Kernel SVM to the Training set ----------------------------- #

# install.packages('e1071')
library(e1071)
classifier = svm(formula = Purchased ~ .,
                 data = training_set,
                 type = 'C-classification',
                 kernel = 'radial')

# -------------------------------------------- Predicting the Test set results -------------------------------- #

y_pred = predict(classifier, newdata = test_set[-3])
y_pred

# ------------------------------------------------- Confusion Matrix ------------------------------------------- #

cm = table(test_set[, 3], y_pred)
cm

# ------------------------------------------- Applying k-Fold Cross Validation --------------------------------- #

# install.packages('caret')
library(caret)
folds = createFolds(training_set$Purchased, k = 10)
cv = lapply(folds, function(x) {
  training_fold = training_set[-x, ]
  test_fold = training_set[x, ]
  classifier = svm(formula = Purchased ~ .,
                   data = training_fold,
                   type = 'C-classification',
                   kernel = 'radial')
  y_pred = predict(classifier, newdata = test_fold[-3])
  cm = table(test_fold[, 3], y_pred)
  accuracy = (cm[1,1] + cm[2,2]) / (cm[1,1] + cm[2,2] + cm[1,2] + cm[2,1])
  return(accuracy)
})
accuracy = mean(as.numeric(cv))
accuracy
cv

# --------------------------------------- Visualising the Training Set results --------------------------------- #

library(ElemStatLearn)

set = training_set

train1 = seq(min(set[, 1]) - 1, max(set[, 1]) + 1, by = 0.01)
train2 = seq(min(set[, 2]) - 1, max(set[, 2]) + 1, by = 0.01)

grid_set = expand.grid(train1, train2)

colnames(grid_set) = c('Age', 'EstimatedSalary')

y_grid = predict(classifier, newdata = grid_set)

# Plotting
plot(set[, -3],
     main = 'K-Fold Cross Validation (Training set)',
     xlab = 'Age', ylab = 'Estimated Salary',
     xlim = range(train1), ylim = range(train2))

# Regression Line
contour(train1, train2, matrix(as.numeric(y_grid), length(train1), length(train2)), add = TRUE)

# Giving Colours
points(grid_set, pch = '.', col = ifelse(y_grid == 1, 'springgreen3', 'tomato'))
points(set, pch = 21, bg = ifelse(set[, 3] == 1, 'green4', 'red3'))

# ------------------------------------------- Visualising the Test Set results --------------------------------- #

library(ElemStatLearn)

set = test_set

test1 = seq(min(set[, 1]) - 1, max(set[, 1]) + 1, by = 0.01)
test2 = seq(min(set[, 2]) - 1, max(set[, 2]) + 1, by = 0.01)

grid_set = expand.grid(test1, test2)

colnames(grid_set) = c('Age', 'EstimatedSalary')

y_grid = predict(classifier, newdata = grid_set)

# Plotting
plot(set[, -3], main = 'K-Fold Cross Validation (Test set)',
     xlab = 'Age', ylab = 'Estimated Salary',
     xlim = range(test1), ylim = range(test2))

# Regression Line
contour(test1, test2, matrix(as.numeric(y_grid), length(test1), length(test2)), add = TRUE)

# Giving Colours
points(grid_set, pch = '.', col = ifelse(y_grid == 1, 'springgreen3', 'tomato'))
points(set, pch = 21, bg = ifelse(set[, 3] == 1, 'green4', 'red3'))