How can I drop columns by name in a data frame

We can Drop Columns by name in a data frame using the following two methods:

Create a data frame

The following code creates a sample data frame which we will use for demonstration.

set.seed(556)

    mydata <- data.frame(m=letters[1:5], x=runif(5,10,50), y=sample(5), z=rnorm(5))

# Delete column by name

Method I :

One of the easiest ways to drop columns is by using the subset() function.

The following code tells R to drop variables x and z.

The '-' sign indicates dropping variables.

Note: Don't specify the variable names in quotes when using the subset() function.

df = subset(mydata, select = -c(x,z) )

> mydata

  m        x y           z

1 a 33.83910 2 -1.02569136

2 b 23.50851 3  0.59367584

3 c 22.91966 1 -0.06436851

4 d 33.18065 4 -0.04719129

5 e 13.79128 5 -1.80186137

> df

  m y

1 a 2

2 b 3

3 c 1

4 d 4

5 e 5

Method II :

The function names() returns all the column names and the '!' sign indicates negation.

drop <- c("x","z") #we are creating a character vector named drop in which we are storing column names x and z

df = mydata[,!(names(mydata) %in% drop)] #Selecting all the variables except the column names specified in the vector drop. The '!' sign indicates negation.

> df

  m y

1 a 2

2 b 3

3 c 1

4 d 4

5 e 5

It can also be written like : df = mydata[,!(names(mydata) %in% c("x","z"))]

> set.seed(556)

> mydata <- data.frame(m=letters[1:5], x=runif(5,10,50), y=sample(5), z=rnorm(5))

> df = mydata[,!(names(mydata) %in% c("x","z"))]

> df

  m y

1 a 2

2 b 3

3 c 1

4 d 4

5 e 5