*17*

One warning you may encounter in R is:

Warning message: In mean.default(df) : argument is not numeric or logical: returning NA

This warning occurs when you attempt to calculate the mean of some object in R that is not numerical or logical.

This tutorial shares exactly how to handle this warning in practice.

**How to Reproduce the Warning**

Suppose we create the following data frame in R:

**#create data frame
df frame(team=c('A', 'B', 'C', 'D', 'E'),
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
team points assists rebounds
1 A 99 33 30
2 B 90 28 28
3 C 86 31 24
4 D 88 39 24
5 E 95 34 28
**

If we attempt to calculate the mean of a character column or if we attempt to calculate the mean of the entire data frame, weâ€™ll receive a warning:

**#attempt to calculate mean of character column
mean(df$team)
Warning message:
In mean.default(df$team) : argument is not numeric or logical: returning NA
#attempt to calculate mean of entire data frame
mean(df)
Warning message:
In mean.default(df) : argument is not numeric or logical: returning NA
**

The **mean()** function only takes a numeric vector as an argument, which explains why we receive a warning in both scenarios.

**How to Handle the Warning**

The way to handle this warning is to only use the **mean()** function with numeric vectors.

For example, we could calculate the mean of the points column since itâ€™s numeric:

**#calculate mean of points column
mean(df$points)
[1] 91.6
**

Or we could use the **sapply()** function to calculate the mean of every column in the data frame:

**#calculate mean of every column in data frame
sapply(df, mean, 2)
team points assists rebounds
NA 90 33 28
Warning message:
In mean.default(X[[i]], ...) :
argument is not numeric or logical: returning NA**

Weâ€™re able to calculate the mean of each numeric column, but still receive a warning message since we attempted to calculate the mean of the â€˜teamâ€™ character column.

To avoid this warning entirely, we could use the **sapply()** function with just the three numeric columns:

**#calculate mean of each numeric column
sapply(df[c('points', 'assists', 'rebounds')], mean, 2)
points assists rebounds
90 33 28**

Notice that the mean of each numeric column is successfully shown and we receive no warning message.

**Additional Resources**

The following tutorials explain how to fix other common errors in R:

How to Fix: the condition has length > 1 and only the first element will be used

How to Fix: non-numeric argument to binary operator

How to Fix: dim(X) must have a positive length

How to Fix: error in select unused arguments