You can use the following basic syntax to calculate the standard deviation of columns in R:
#calculate standard deviation of one column sd(df$col1) #calculate standard deviation of all columns sapply(df, sd) #calculate standard deviation of specific columns sapply(df[c('col1', 'col2', 'col5')], sd)
The following examples show how to use this syntax in practice with the following data frame:
#create data frame df frame(team=c('A', 'B', 'C', 'D', 'E'), points=c(99, 91, 86, 88, 95), assists=c(33, 28, 31, 39, 34), rebounds=c(30, 28, 24, 24, 28)) #view data frame df team points assists rebounds 1 A 99 33 30 2 B 91 28 28 3 C 86 31 24 4 D 88 39 24 5 E 95 34 28
Example 1: Standard Deviation of One Column
The following code shows how to calculate the standard deviation of one column in the data frame:
#calculate standard deviation of 'points' column
sd(df$points)
[1] 5.263079
The standard deviation of values in the ‘points’ column is 5.263079.
Example 2: Standard Deviation of All Columns
The following code shows how to calculate the standard deviation of every column in the data frame:
#calculate standard deviation of all columns in data frame
sapply(df, sd)
team points assists rebounds
NA 5.263079 4.062019 2.683282
Warning message:
In var(if (is.vector(x) || is.factor(x)) x else as.double(x), na.rm = na.rm) :
NAs introduced by coercion
Since the ‘team’ column is a character variable, R returns NA and gives us a warning.
However, it successfully computes the standard deviation of the other three numeric columns.
Example 3: Standard Deviation of Specific Columns
The following code shows how to calculate the standard deviation of specific columns in the data frame:
#calculate standard deviation of 'points' and 'rebounds' columns
sapply(df[c('points', 'rebounds')], sd)
points rebounds
5.263079 2.683282
Note that we could use column index values to select columns as well:
#calculate standard deviation of 'points' and 'rebounds' columns
sapply(df[c(2, 4)], sd)
points rebounds
5.263079 2.683282
Additional Resources
The following tutorials explain how to perform other common functions in R:
How to Calculate Standard Deviation of Rows in R
How to Calculate the Mean of Multiple Columns in R
How to Find the Max Value Across Multiple Columns in R
How to Select Specific Columns in R