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R Data Analysis Cookbook - Second Edition by Kuntal Ganguly

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How to do it...

To perform variable selection in linear regression, perform the following steps:

  1. Load the caret and MASS packages:
> library(caret) 
> library(MASS) 
  1. Read the data:
> auto <- read.csv("auto-mpg.csv") 
  1. Convert the categorical variable cylinders into a factor with appropriate renaming of the levels:
> auto$cylinders <- factor(auto$cylinders,  levels = c(3,4,5,6,8), labels = c("3cyl", "4cyl", "5cyl", "6cyl", "8cyl"))
  1. Create partitions:
> set.seed(1000) 
> t.idx <- createDataPartition(auto$mpg, p = 0.7, list = FALSE) 
  1. See the names of the variables in the data frame:
> names(auto) 
[1] "No"           "mpg"          
[3] "cylinders"    "displacement" 
[5] "horsepower"   "weight"       
[7] "acceleration" "model_year"   
[9] "car_name"     
  1. Build the linear regression ...

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