# How to Compare Two Columns in R (With Examples)

Often you may want to compare two columns in R and write the results of the comparison to a third column.

You can easily do this by using the following syntax:

```df\$new_col <- ifelse(df\$col1 > df\$col2, 'A',
ifelse(df\$col1 < df\$col2, 'B', 'C'))
```

This single line of code does the following:

• If column 1 is greater than column 2 then write ‘A’ as the output to the third column.
• Otherwise, if column 1 is less than column 2 then write ‘B’ as the output..
• Otherwise, write ‘C’ as the output.

The following example shows how to use this code in practice.

### Example: Compare Two Columns in R

Suppose we have the following data frame that shows the number of goals scored by two soccer teams in five different matches:

```#create data frame
df <- data.frame(A_points=c(1, 3, 3, 3, 5),
B_points=c(4, 5, 2, 3, 2))

#view data frame
df

A_points B_points
1        1        4
2        3        5
3        3        2
4        3        3
5        5        2
```

We can use the following code to compare the number of goals by row and output the winner of the match in a third column:

```#compare A_points and B_points and output results to new column titled winner
df\$winner <- ifelse(df\$A_points > df\$B_points, 'A',
ifelse(df\$A_points < df\$B_points, 'B', 'Tie'))

#view data frame
df

A_points B_points winner
1        1        4      B
2        3        5      B
3        3        2      A
4        3        3    Tie
5        5        2      A```

The results of the comparison are shown in the new column called winner.