How to Aggregate Multiple Columns in R (With Examples)


We can use the aggregate() function in R to produce summary statistics for one or more variables in a data frame.

This function uses the following basic syntax:

aggregate(sum_var ~ group_var, data = df, FUN = mean)

where:

  • sum_var: The variable to summarize
  • group_var: The variable to group by
  • data: The name of the data frame
  • FUN: The summary statistic to compute

This tutorial provides several examples of how to use this function to aggregate one or more columns at once in R, using the following data frame as an example:

#create data frame
df <- data.frame(team=c('A', 'A', 'A', 'B', 'B', 'B', 'C', 'C'),
                 conf=c('E', 'E', 'W', 'W', 'W', 'W', 'W', 'W'),
                 points=c(1, 3, 3, 4, 5, 7, 7, 9),
                 rebounds=c(7, 7, 8, 3, 2, 7, 14, 13))

#view data frame
df

  team conf points rebounds
1    A    E      1        7
2    A    E      3        7
3    A    W      3        8
4    B    W      4        3
5    B    W      5        2
6    B    W      7        7
7    C    W      7       14
8    C    W      9       13

Example 1: Summarize One Variable & Group by One Variable

The following code shows how to find the mean points scored, grouped by team:

#find mean points scored, grouped by team
aggregate(points ~ team, data = df, FUN = mean, na.rm = TRUE)

  team   points
1    A 2.333333
2    B 5.333333
3    C 8.000000

Example 2: Summarize One Variable & Group by Multiple Variables

The following code shows how to find the mean points scored, grouped by team and conference:

#find mean points scored, grouped by team and conference
aggregate(points ~ team + conf, data = df, FUN = mean, na.rm = TRUE)

  team conf   points
1    A    E 2.000000
2    A    W 3.000000
3    B    W 5.333333
4    C    W 8.000000

Example 3: Summarize Multiple Variables & Group by One Variable

The following code shows how to find the mean points and the mean rebounds, grouped by team:

#find mean points scored, grouped by team and conference
aggregate(cbind(points,rebounds) ~ team, data = df, FUN = mean, na.rm = TRUE)

  team   points  rebounds
1    A 2.333333  7.333333
2    B 5.333333  4.000000
3    C 8.000000 13.500000

Example 4: Summarize Multiple Variables & Group by Multiple Variables

The following code shows how to find the mean points and the mean rebounds, grouped by team and conference:

#find mean points scored, grouped by team and conference
aggregate(cbind(points,rebounds) ~ team + conf, data = df, FUN = mean, na.rm = TRUE)

  team conf   points rebounds
1    A    E 2.000000      7.0
2    A    W 3.000000      8.0
3    B    W 5.333333      4.0
4    C    W 8.000000     13.5

Additional Resources

How to Calculate the Mean of Multiple Columns in R
How to Sum Specific Columns in R
How to Sum Specific Rows in R

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