You can use the following basic syntax to calculate the standard deviation of rows in R:

row_stdev <- apply(df, 1, sd, na.rm=TRUE)

The following example shows how to use this syntax in R.

**Example: Calculate Standard Deviation of Rows in R**

Suppose we have the following data frame in R:

#create data frame df <- data.frame(game1=c(12, 15, 15, 18, 29, 30, 31), game2=c(15, 17, 17, 16, 29, 8, 14), game3=c(8, 22, 27, 35, 29, 22, 17)) #view data frame df game1 game2 game3 1 12 15 8 2 15 17 22 3 15 17 27 4 18 16 35 5 29 29 29 6 30 8 22 7 31 14 17

We can use the following syntax to calculate the standard deviation of the values in each row:

#calculate standard deviation of each row row_stdev <- apply(df, 1, sd, na.rm=TRUE) #view standard deviation of each row row_stdev [1] 3.511885 3.605551 6.429101 10.440307 0.000000 11.135529 9.073772

From the output we can see:

- The standard deviation of values in the first row is
**3.511885**. - The standard deviation of values in the second row is
**3.605551**. - The standard deviation of values in the third row is
**6.429101**.

And so on.

If we’d like, we can also use the transform() function to add a new column to the data frame that shows the standard deviation of values in each row:

#add column that displays standard deviation of each row df <- transform(df, row_stdev=apply(df, 1, sd, na.rm=TRUE)) #view updated data frame df game1 game2 game3 row_stdev 1 12 15 8 3.511885 2 15 17 22 3.605551 3 15 17 27 6.429101 4 18 16 35 10.440307 5 29 29 29 0.000000 6 30 8 22 11.135529 7 31 14 17 9.073772

The new column called **row_stdev** displays the standard deviation of values in each row.

**Note:** The standard deviation of values in row 5 is equal to zero because each of the values is the same, thus there is no “deviation” at all in the values.

**Related:** How to Interpret a Standard Deviation of Zero

**Additional Resources**

The following tutorials explain how to perform other common functions in R:

How to Calculate Standard Deviation Using dplyr

How to Calculate Weighted Standard Deviation in R

How to Calculate Pooled Standard Deviation in R