You can use the following methods to add a suffix to column names in R:

Method 1: Add Suffix to All Column Names

colnames(df) <- paste(colnames(df), 'my_suffix', sep = '_')

Method 2: Add Suffix to Specific Column Names

colnames(df)[c(1, 3)] <- paste(colnames(df)[c(1, 3)], 'my_suffix', sep = '_')

The following examples show how to use each method with the following data frame:

#create data frame
df <- data.frame(points=c(99, 90, 86, 88, 95),
                 assists=c(33, 28, 31, 39, 34),
                 rebounds=c(30, 28, 24, 24, 28))	

#view data frame
df

  points assists rebounds
1     99      33       30
2     90      28       28
3     86      31       24
4     88      39       24
5     95      34       28

Example 1: Add Suffix to All Column Names

The following code shows how to add the suffix ‘_total‘ to all column names:

#add suffix '_total' to all column names
colnames(df) <- paste(colnames(df), 'total', sep = '_') 

#view updated data frame
df

  points_total assists_total rebounds_total
1           99            33             30
2           90            28             28
3           86            31             24
4           88            39             24
5           95            34             28

Notice that the suffix ‘_total‘ has been appended to the end of each column name.

Example 2: Add Suffix to Specific Column Names

The following code shows how to add the suffix ‘_total‘ to specific column names:

#add suffix '_total' to column names in index positions 1 and 3
colnames(df)[c(1, 3)] <- paste(colnames(df)[c(1, 3)], 'total', sep = '_') 

#view updated data frame
df

  points_total assists rebounds_total
1           99      33             30
2           90      28             28
3           86      31             24
4           88      39             24
5           95      34             28

Notice that the suffix ‘_total‘ has only been appended to the columns in index positions 1 and 3.