Create 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