Random Forest in R, Random forest created by an aggregating tree and this can be utilized for characterization and regression. One of the major benefits is its stays away from overfitting. So, learn R Programming Training Course in Bangalore
The random forest can manage a large number of features and it assists with distinguishing the important attributes.
The random forest contains two user-friendly parameters ntree and mtry.
ntree-ntree as a matter of course is 500 trees.
mtry-variables randomly tests as up-and-comers at each split.
Random Forest Steps
1. Draw ntree bootstrap tests.
2. For each bootstrap, grow an un-pruned tree by picking the best parted dependent on a random example of mtry predictors at every hub
3. Predict new data utilizing majority votes in favor of order and average for regression dependent on ntree trees.
Burden Library
library(randomForest)
library(datasets)
library(caret)
Getting Data
data<-iris
str(data)
The datasets contain 150 observations and 5 variables. Species considered as response variables. Species variable ought to be a factor variable.
data$Species <-as.factor(data$Species)
table(data$Species)
setosa versicolor virginica
50
From the above results, we can recognize that our data set is adjusted.
Correlation investigation in R
Data Partition
Lets start with random seed so the result will be repeatable and store train and test data.
set.seed(222)
ind <-sample(2, nrow(data), replace = TRUE, prob = c(0.7, 0.3))
train <-data[ind==1,]
test <-data[ind==2,]
106 observations in train data set and 44 observatons in test data.
Random Forest in R
rf <-randomForest(Species~., data=train, proximity=TRUE) print(rf)
Call:
randomForest(formula = Species ~ ., data = train)
Kind of random forest: characterization
Number of trees: 500
No. of variables tried at each split: 2
OOB gauge of error rate: 2.83%
Disarray matrix:
setosa versicolor virginica class.error
setosa 35 0 0.00000000
versicolor 0 35 1 0.02777778
virginica 0 2 33 0.05714286
Out of sack error is 2.83%, so the train data set model accuracy is around 97%.
tidyverse complete tutorial
Ntree is 500 and mtry is 2
Prediction and Confusion Matrix – train data
p1 <-predict(rf, train)
confusionMatrix(p1, train$ Species)
Disarray Matrix and Statistics
Reference
Prediction setosa versicolor virginica
setosa 35 0
versicolor 0 36 0
virginica 0 35
Overall Statistics
Accuracy : 1
95% CI : (0.9658, 1)
No Information Rate : 0.3396
P-Value [Acc > NIR] : < 2.2e-16
Kappa : 1
Mcnemar’s Test P-Value : NA
Insights by Class:
Class: setosa Class: versicolor Class: virginica
Affectability 1.0000
Explicitness 1.0000
Pos Pred Value 1.0000
Neg Pred Value 1.0000
Prevalence 0.3302 0.3396 0.3302
Location Rate 0.3302 0.3396 0.3302
Location Prevalence 0.3302 0.3396 0.3302
Adjusted Accuracy 1.0000
Train data accuracy is 100% that shows every one of the qualities grouped correctly.
Naive Bayes Classification in R
Prediction and Confusion Matrix – test data
p2 <-predict(rf, test)
confusionMatrix(p2, test$ Species)
Disarray Matrix and Statistics
Reference
Prediction setosa versicolor virginica
setosa 15 0
versicolor 0 11 1
virginica 0 3 14
Overall Statistics
Accuracy : 0.9091
95% CI : (0.7833, 0.9747)
No Information Rate : 0.3409
– P-Value [Acc > NIR] : 5.448e-15
Kappa : 0.8634
Mcnemar’s Test P-Value : NA
Insights by Class:
Class: setosa Class: versicolor Class: virginica
Affectability 1.0000 0.7857 0.9333
Explicitness 1.0000 0.9667 0.8966
Pos Pred Value 1.0000 0.9167 0.8235
Neg Pred Value 1.0000 0.9062 0.9630
Prevalence 0.3409 0.3182 0.3409
Discovery Rate 0.3409 0.2500 0.3182
Discovery Prevalence 0.3409 0.2727 0.3864
Adjusted Accuracy 1.0000 0.8762 0.9149
Test data accuracy is 90%
Error rate of Random Forest
plot(rf)
The model is predicted with high accuracy, with no requirement for further tuning. However, we can tune a number of trees and mtry premise beneath the capacity.
LSTM networks in R
Tune mtry
t <-tuneRF(train[,- 5], train[,5],
stepFactor = 0.5,
plot = TRUE,
ntreeTry = 150,
trace = TRUE,
improve = 0.05)
No. of hubs for the trees
hist(treesize(rf),
main = “No. of Nodes for the Trees”,
col = “green”)
Variable Importance
varImpPlot(rf,
sort = T,
n.var = 10,
main = “Top 10 – Variable Importance”)
importance(rf)
MeanDecreaseGini
Sepal.Length 7.170376
Sepal.Width 1.318423
Petal.Length 32.286286
Petal.Width 29.117348
Petal.Length is the main attribute followed by Petal.Width.
Partial Dependence Plot
partialPlot(rf, train, Petal.Width, “setosa”)
The inference ought to be, on the off chance that the petal width is under 1.5, higher odds of grouping into Setosa class.
Multi-dimensional Scaling Plot of Proximity Matrix
Measurement plot likewise can create from random forest model.
MDSplot(rf, train$Species)
