How to match and replace column names stored in R data frames in R-Programming?

R ProgrammingServer Side ProgrammingProgramming

If we have a data frame that contains a column of column names which matches with the column names of a data frame and another column that has different values then we can set these different values as the new column names of the data frame having matched column names.

This can be done with the help of match function. Check out the below Examples to understand how it works.

Example 1

Following snippet creates a sample data frame −

x1<-rnorm(20)
x2<-rnorm(20)
x3<-rnorm(20)
df1<-data.frame(x1,x2,x3)
df1

The following dataframe is created

            x1          x2           x3
1   0.76231437 -0.18459872 -0.836848620
2   0.31998649  1.24599469  0.096976964
3   0.11319510 -1.19200362 -0.824255747
4   0.47570366  0.24791478  0.355295166
5  -0.84546806  1.05928526 -1.073653485
6  -1.89667914  0.92187888  1.552141225
7  -1.81604483  0.05974304 -0.244209195
8   0.05762202  0.14238099  0.957877205
9  -0.79539907  0.42396450  0.219413291
10  0.47248362  2.44519391 -0.126831024
11  0.91802738 -0.84282349  1.577785667
12 -1.30378165  1.04226653 -0.528164742
13  0.88999575  1.74773475  1.409087713
14 -0.43192360  0.11203207  0.976614195
15 -0.68683934  0.67849795 -0.004272223
16 -0.68894471  1.33377663 -0.397701119
17  1.06729808 -0.04649078  0.578908343
18 -0.73322670 -0.52255298  0.355650527
19  0.28593460 -1.19460885 -0.094308012
20  0.76086277 -0.38646442 -0.484786025

Add the following code to the above snippet −

x1<-rnorm(20)
x2<-rnorm(20)
x3<-rnorm(20)
df1<-data.frame(x1,x2,x3)
df1_col<-data.frame(Var1=c("x","y","z"),Var2=c("x1","x2","x3"))
df1_col

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

  Var1 Var2
1   x    x1
2   y    x2
3   z    x3

To change the column names of df1 to values in Var1 in df1_col on the above created data frame, add the following code to the above snippet −

x1<-rnorm(20)
x2<-rnorm(20)
x3<-rnorm(20)
df1<-data.frame(x1,x2,x3)
df1_col<-data.frame(Var1=c("x","y","z"),Var2=c("x1","x2","x3"))
names(df1) <- df1_col$Var1[match(names(df1),df1_col$Var2)]
df1

Output

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

           x y z
1   0.76231437 -0.18459872 -0.836848620
2   0.31998649  1.24599469  0.096976964
3   0.11319510 -1.19200362 -0.824255747
4   0.47570366  0.24791478  0.355295166
5  -0.84546806  1.05928526 -1.073653485
6  -1.89667914  0.92187888  1.552141225
7  -1.81604483  0.05974304 -0.244209195
8   0.05762202  0.14238099  0.957877205
9  -0.79539907  0.42396450  0.219413291
10  0.47248362  2.44519391 -0.126831024
11  0.91802738 -0.84282349  1.577785667
12 -1.30378165  1.04226653 -0.528164742
13  0.88999575  1.74773475  1.409087713
14 -0.43192360  0.11203207  0.976614195
15 -0.68683934  0.67849795 -0.004272223
16 -0.68894471  1.33377663 -0.397701119
17  1.06729808 -0.04649078  0.578908343
18 -0.73322670 -0.52255298  0.355650527
19  0.28593460 -1.19460885 -0.094308012
20  0.76086277 -0.38646442 -0.484786025

Example 2

Following snippet creates a sample data frame −

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

The following dataframe is created

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

Add the following code to the above snippet −

a<-rpois(20,2)
b<-rpois(20,5)
c<-rpois(20,2)
df2<-data.frame(a,b,c)
df2_col<-data.frame(Ranks=c("Rank1","Rank2","Rank3"),Var=c("a","b","c"))
df2_col

Output

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

  Ranks Var
1 Rank1  a
2 Rank2  b
3 Rank3  c

To change the column names of df2 to values in Var in df2_col on the above created data frame, add the following code to the above snippet −

a<-rpois(20,2)
b<-rpois(20,5)
c<-rpois(20,2)
df2<-data.frame(a,b,c)
df2_col<-data.frame(Ranks=c("Rank1","Rank2","Rank3"),Var=c("a","b","c"))
names(df2)<-df2_col$Ranks[match(names(df2),df2_col$Var)]
df2

Output

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

 Rank1 Rank2 Rank3
1    3     6    0
2    1     7    5
3    2     5    3
4    1     1    2
5    4     9    2
6    0     3    3
7    1     6    1
8    0     6    3
9    4     6    2
10   1     4    2
11   3     2    2
12   0     6   2
13   1     4   2
14   0     7   2
15   4     2   2
16   2     4   5
17   2     3   0
18   4     5   4
19   3     3   1
20   3     4   2
raja
Published on 01-Nov-2021 05:57:48
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