Question:

How will you drop variables using indices in a data frame?

Answer:

Let’s take a dataframe df<-data.frame(v1=c(1:5),v2=c(2:6),v3=c(3:7),v4=c(4:8))

df

##   v1 v2 v3 v4

## 1  1  2  3  4

## 2  2  3  4  5

## 3  3  4  5  6

## 4  4  5  6  7

## 5  5  6  7  8

Suppose we want to drop variables v2 & v3 , the variables v2 and v3 can be dropped using negative indicies as follows-

df1<-df[-c(2,3)]

df1

##   v1 v4

## 1  1  4

## 2  2  5

## 3  3  6

## 4  4  7

## 5  5  8

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