You can use the **sum()** function in R to find the sum of values in a vector.

This function uses the following basic syntax:

**sum(x, na.rm=FALSE)**

where:

**x**: Name of the vector.**na.rm**: Whether to ignore NA values. Default is FALSE.

The following examples show how to use this function in practice.

**Example 1: Sum Values in Vector**

The following code shows how to sum the values in a vector:

#create vector x <- c(3, 6, 7, 12, 15) #sum values in vector sum(x) [1] 43

If there happen to be NA values in the vector, you can use **na.rm=TRUE** to ignore the missing values when calculating the mean:

#create vector with some NA values x <- c(3, NA, 7, NA, 15) #sum values in vector sum(x, na.rm=TRUE) [1] 25

**Example 2: Sum Values in Data Frame Column**

The following code shows how to sum the values in a specific column of a data frame:

#create data frame df <- data.frame(var1=c(1, 3, 3, 4, 5), var2=c(7, 7, 8, 3, 2), var3=c(3, 3, 6, 6, 8), var4=c(1, 1, 2, 8, 9)) #view data frame df var1 var2 var3 var4 1 1 7 3 1 2 3 7 3 1 3 3 8 6 2 4 4 3 6 8 5 5 2 8 9 #sum values in 'var1' column sum(df$var1) [1] 16

**Example 3: Sum Values in Several Data Frame Columns**

The following code shows how to use the **sapply()** function to sum the values in several columns of a data frame:

#create data frame df <- data.frame(var1=c(1, 3, 3, 4, 5), var2=c(7, 7, 8, 3, 2), var3=c(3, 3, 6, 6, 8), var4=c(1, 1, 2, 8, 9)) #view data frame df var1 var2 var3 var4 1 1 7 3 1 2 3 7 3 1 3 3 8 6 2 4 4 3 6 8 5 5 2 8 9 #sum values in 'var1' and 'var3' columns sapply(df[ , c('var1', 'var3')], sum) var1 var3 16 26

**Additional Resources**

How to Perform a COUNTIF Function in R

How to Perform a SUMIF Function in R

How to Use rowSums() Function in R

How to Use colSums() Function in R