#It is used to find out which column contains the string provide in grepl function
data(mtcars)
colnames(mtcars)
#rownames(mtcars)

#data with those columns which has string 'a'
mtcars[,grepl('a',colnames(mtcars))]

# data with those column which doesnt has 'a'
mtcars[,!grepl('a',colnames(mtcars))]