How to change the name of single column using setNames in R?

To change the name of single column using setNames, we would need to specify the column name that needs to be changed.

For example, if we have a data frame called df that contains three columns say Var1, var2, and Var3 and we want to change var2 to Var2 then we can use the command as follows −

setNames(df,replace(names(df),names(df)=="var2","Var2"))

Example 1

Following snippet creates a sample data frame −

x<-rnorm(20)
x1<-rnorm(20)
df1<-data.frame(x,x1)
df1

Output

The following dataframe is created −

       x            x1
1   0.885142314  -0.18025261
2  -0.048954839   0.87720112
3   0.896212666  -0.53714354
4   0.539095496  -0.19380810
5  -1.706763224   0.79608177
6  -1.628122107  -1.17570164
7  -1.000949495   0.09243436
8   1.344899293  -0.34504828
9   0.290659812   0.57493564
10 -1.366119792   0.39442545
11 -0.002044629  -0.60124159
12  1.056147083  -0.05670359
13  1.245766258  -0.91321178
14  1.202689649   0.42440362
15 -1.238028330  -1.31709063
16  0.962875354   1.43057923
17  0.692604922  -0.60277152
18  1.721352577   0.67629134
19 -2.373829503  -0.09540660
20  0.031280271   1.90790870

In order to change the name of column x1 to y, add the following code to the above snippet −

x<-rnorm(20)
x1<-rnorm(20)
df1<-data.frame(x,x1)
setNames(df1,replace(names(df1),names(df1)=="x1","y"))

Output

If you execute all the above given codes as a single program, it generates the following output −

         x           y
1   0.885142314  -0.18025261
2  -0.048954839   0.87720112
3   0.896212666  -0.53714354
4   0.539095496  -0.19380810
5  -1.706763224   0.79608177
6  -1.628122107  -1.17570164
7  -1.000949495   0.09243436
8   1.344899293  -0.34504828
9   0.290659812   0.57493564
10 -1.366119792   0.39442545
11 -0.002044629  -0.60124159
12  1.056147083  -0.05670359
13  1.245766258  -0.91321178
14  1.202689649   0.42440362
15 -1.238028330  -1.31709063
16  0.962875354   1.43057923
17  0.692604922  -0.60277152
18  1.721352577   0.67629134
19 -2.373829503  -0.09540660
20  0.031280271   1.90790870

Example 2

Following snippet creates a sample data frame −

a<-rpois(20,5)
a_2<-rpois(20,2)
df2<-data.frame(a,a_2)
df2

Output

The following dataframe is created −

   a a_2
1  5  7
2  3  2
3  7  2
4  5  0
5  6  0
6  4  1
7  8  3
8  6  1
9  7  2
10 6  3
11 4  0
12 3  2
13 5  0
14 7  2
15 3  1
16 9  3
17 2  2
18 4  1
19 2  7
20 1  1

In order to change the name of column a_2 to b, add the following code to the above snippet −

a<-rpois(20,5)
a_2<-rpois(20,2)
df2<-data.frame(a,a_2)
df2<-data.frame(a,a_2) 
setNames(df2,replace(names(df2),names(df2)=="a_2","b"))

Output

If you execute all the above given codes as a single program, it generates the following output −

   a  b
1  5  7
2  3  2
3  7  2
4  5  0
5  6  0
6  4  1
7  8  3
8  6  1
9  7  2
10 6  3
11 4  0
12 3  2
13 5  0
14 7  2
15 3  1
16 9  3
17 2  2
18 4  1
19 2  7
20 1  1