The colSums() function in R can be used to calculate the sum of the values in each column of a matrix or data frame in R.
This function uses the following basic syntax:
colSums(x, na.rm=FALSE)
where:
- x: Name of the matrix or data frame.
- na.rm: Whether to ignore NA values. Default is FALSE.
The following examples show how to use this function in practice.
Example 1: Use colSums() with Data Frame
The following code shows how to use colSums() to find the sum of the values in each column of a data frame:
#create data frame df frame(var1=c(1, 3, 3, 4, 5), var2=c(7, 2, 5, 3, 2), var3=c(3, 3, 6, 6, 8), var4=c(1, 1, 2, 14, 9)) #view data frame df var1 var2 var3 var4 1 1 7 3 1 2 3 2 3 1 3 3 5 6 2 4 4 3 6 14 5 5 2 8 9 #find sum of each column colSums(df) var1 var2 var3 var4 16 19 26 27
Here’s how to interpret the output:
- The sum of values in the ‘var1’ column is 16.
- The sum of values in the ‘var2’ column is 19.
- The sum of values in the ‘var3’ column is 26.
- The sum of values in the ‘var4’ column is 27.
Example 2: Use colSums() with NA Values in Data Frame
The following code shows how to use colSums() to find the sum of the values in each column of a data frame when there are NA values in some columns:
#create data frame with some NA values df frame(var1=c(1, 3, 3, 4, 5), var2=c(7, NA, NA, 3, 2), var3=c(3, 3, 6, 6, 8), var4=c(1, 1, 2, NA, 9)) #view data frame df var1 var2 var3 var4 1 1 7 3 1 2 3 NA 3 1 3 3 NA 6 2 4 4 3 6 NA 5 5 2 8 9 #find sum of each column colSums(df, na.rm=TRUE) var1 var2 var3 var4 16 12 26 13
Example 3: Use colSums() with Specific Columns
The following code shows how to use colSums() to find the sum of the values in specific columns of a data frame:
#create data frame with some NA values df frame(var1=c(1, 3, 3, 4, 5), var2=c(7, NA, NA, 3, 2), var3=c(3, 3, 6, 6, 8), var4=c(1, 1, 2, NA, 9)) #view data frame df var1 var2 var3 var4 1 1 7 3 1 2 3 NA 3 1 3 3 NA 6 2 4 4 3 6 NA 5 5 2 8 9 #find sum of columns 1, 3, and 4 colSums(df[, c(1, 3, 4)], na.rm=TRUE) var1 var3 var4 16 26 13
Additional Resources
How to Sum Specific Columns in R (With Examples)
How to Sum Specific Rows in R (With Examples)