How to Fix in R: Error in aggregate.data.frame(): arguments must have same length

One error you may encounter in R is:

Error in aggregate.data.frame(as.data.frame(x), ...) : 
  arguments must have same length

This error occurs when you attempt to use the aggregate() function to summarize the values in one or more columns of a data frame in R but fail to specify the name of the data frame when referencing the columns.

This tutorial shares exactly how to fix this error.

How to Reproduce the Error

Suppose we have the following data frame in R:

#create data frame
df <- data.frame(team=c('A', 'A', 'A', 'A', 'A', 'B', 'B', 'B', 'C', 'C'),
                 points=c(5, 9, 12, 14, 14, 13, 10, 6, 15, 18))

#view data frame
df

   team points
1     A      5
2     A      9
3     A     12
4     A     14
5     A     14
6     B     13
7     B     10
8     B      6
9     C     15
10    C     18

Now suppose we attempt to use the aggregate() function to calculate the mean points value, grouped by team:

#attempt to calculate mean points value by team
aggregate(df$points, list('team'), FUN=mean)

Error in aggregate.data.frame(as.data.frame(x), ...) : 
  arguments must have same length

We receive an error because we failed to specify the name of the data frame in the list() argument.

How to Fix the Error

The way to fix this error is to simply use df$team instead of just ‘team’ in the list() argument:

#calculate mean points value by team
aggregate(df$points, list(df$team), FUN=mean)

  Group.1         x
1       A 10.800000
2       B  9.666667
3       C 16.500000

Notice that we don’t receive any error this time because we specified the name of the data frame in the list() argument.

Note that if you use multiple column names in the list() argument then you will need to specify the data frame name for each column name or else you will receive an error.