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debakarr
GitHub Repository: debakarr/machinelearning
 Path: blob/master/Part 10 - Model Selection And Boosting/Grid Search/grid_search.R
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# Grid Search

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# Importing the dataset

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

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dataset = dataset[3:5]

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# Encoding the target feature as factor

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

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# Splitting the dataset into the Training set and Test set

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# install.packages('caTools')

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library(caTools)

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set.seed(123)

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split = sample.split(dataset$Purchased, SplitRatio = 0.75)

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training_set = subset(dataset, split == TRUE)

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test_set = subset(dataset, split == FALSE)

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# Feature Scaling

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

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

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# Fitting Kernel SVM to the Training set

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# install.packages('e1071')

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library(e1071)

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classifier = svm(formula = Purchased ~ .,

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                 data = training_set,

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                 type = 'C-classification',

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                 kernel = 'radial')

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# Predicting the Test set results

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

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# Making the Confusion Matrix

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

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# Applying k-Fold Cross Validation

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# install.packages('caret')

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library(caret)

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folds = createFolds(training_set$Purchased, k = 10)

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cv = lapply(folds, function(x) {

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  training_fold = training_set[-x, ]

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  test_fold = training_set[x, ]

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  classifier = svm(formula = Purchased ~ .,

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                   data = training_fold,

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                   type = 'C-classification',

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                   kernel = 'radial')

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

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

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  accuracy = (cm[1,1] + cm[2,2]) / (cm[1,1] + cm[2,2] + cm[1,2] + cm[2,1])

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  return(accuracy)

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})

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accuracy = mean(as.numeric(cv))

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# Applying Grid Search to find the best parameters

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# install.packages('caret')

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library(caret)

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classifier = train(form = Purchased ~ ., data = training_set, method = 'svmRadial')

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classifier

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classifier$bestTune

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# Visualising the Training set results

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library(ElemStatLearn)

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set = training_set

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X1 = seq(min(set[, 1]) - 1, max(set[, 1]) + 1, by = 0.01)

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X2 = seq(min(set[, 2]) - 1, max(set[, 2]) + 1, by = 0.01)

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grid_set = expand.grid(X1, X2)

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

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y_grid = predict(classifier, newdata = grid_set)

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plot(set[, -3],

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     main = 'Kernel SVM (Training set)',

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     xlab = 'Age', ylab = 'Estimated Salary',

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     xlim = range(X1), ylim = range(X2))

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contour(X1, X2, matrix(as.numeric(y_grid), length(X1), length(X2)), add = TRUE)

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points(grid_set, pch = '.', col = ifelse(y_grid == 1, 'springgreen3', 'tomato'))

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points(set, pch = 21, bg = ifelse(set[, 3] == 1, 'green4', 'red3'))

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# Visualising the Test set results

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library(ElemStatLearn)

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set = test_set

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X1 = seq(min(set[, 1]) - 1, max(set[, 1]) + 1, by = 0.01)

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X2 = seq(min(set[, 2]) - 1, max(set[, 2]) + 1, by = 0.01)

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grid_set = expand.grid(X1, X2)

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

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y_grid = predict(classifier, newdata = grid_set)

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plot(set[, -3], main = 'Kernel SVM (Test set)',

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     xlab = 'Age', ylab = 'Estimated Salary',

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     xlim = range(X1), ylim = range(X2))

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contour(X1, X2, matrix(as.numeric(y_grid), length(X1), length(X2)), add = TRUE)

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points(grid_set, pch = '.', col = ifelse(y_grid == 1, 'springgreen3', 'tomato'))

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points(set, pch = 21, bg = ifelse(set[, 3] == 1, 'green4', 'red3'))

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