# How to create a column of square root in data frames stored in R list?

To create a column of square root in data frames stored in R list, we can follow the below steps −

• First of all, create a list of data frames.

• Then, use lapply function to create a column of square root in data frames stored in the list.

## Example

#### Create the list of data frames

Using data.frame function to create data frames and list function to create the list of those data frames −

df1<-data.frame(x=rpois(25,5))
df2<-data.frame(x=rpois(25,2))
List<-list(df1,df2)
List

## Output

On executing, the above script generates the below output(this output will vary on your system due to randomization) −

[[1]]
x
1  6
2  3
3  3
4  8
5  7
6  3
7  4
8  6
9  5
10 6
11 1
12 1
13 8
14 4
15 5
16 7
17 5
18 4
19 4
20 6
21 8
22 3
23 3
24 7
25 8
[[2]]
x
1  3
2  0
3  0
4  3
5  1
6  4
7  3
8  2
9  3
10 0
11 1
12 2
13 2
14 2
15 2
16 2
17 1
18 2
19 1
20 1
21 4
22 0
23 3
24 0
25 1

Create a column of square root in data frames stored in the list

Using lapply function to create a column of square root in data frames df1 and df2 stored in the list called List as shown below −

df1<-data.frame(x=rpois(25,5))
df2<-data.frame(x=rpois(25,2))
List<-list(df1,df2)
lapply(List,function(x) {
+ x$SquareRoot<-sqrt(x$x)
+ return(x)
+ })

## Output

[[1]]
x SquareRoot
1  6 2.449490
2  3 1.732051
3  3 1.732051
4  8 2.828427
5  7 2.645751
6  3 1.732051
7  4 2.000000
8  6 2.449490
9  5 2.236068
10 6 2.449490
11 1 1.000000
12 1 1.000000
13 8 2.828427
14 4 2.000000
15 5 2.236068
16 7 2.645751
17 5 2.236068
18 4 2.000000
19 4 2.000000
20 6 2.449490
21 8 2.828427
22 3 1.732051
23 3 1.732051
24 7 2.645751
25 8 2.828427
[[2]]
x SquareRoot
1  3 1.732051
2  0 0.000000
3  0 0.000000
4  3 1.732051
5  1 1.000000
6  4 2.000000
7  3 1.732051
8  2 1.414214
9  3 1.732051
10 0 0.000000
11 1 1.000000
12 2 1.414214
13 2 1.414214
14 2 1.414214
15 2 1.414214
16 2 1.414214
17 1 1.000000
18 2 1.414214
19 1 1.000000
20 1 1.000000
21 4 2.000000
22 0 0.000000
23 3 1.732051
24 0 0.000000
25 1 1.000000

Updated on: 09-Nov-2021

97 Views

##### Kickstart Your Career

Get certified by completing the course