# Sum Function in R – sum()

Sum function in R – sum(), is used to calculate the sum of vector elements. sum of a particular column of a dataframe. sum of a group can also calculated using sum() function in R by providing it inside the aggregate function. with sum() function we can also perform row wise sum using dplyr package and also column wise sum lets see an example of each.

• sum of the list of vector elements with NA values
• Sum of a particular column of the dataframe in R
• column wise sum of the dataframe using sum() function
• Sum of the group in R dataframe using aggregate() and dplyr package
• Row wise sum of the dataframe in R using sum() function

#### Syntax for sum function :

sum(x, na.rm = FALSE, …)
• x – numeric vector
• rm- whether NA should be removed, if not, NA will be returned

#### Example of sum function in R

sum of vectors is depicted below.

```# R sum function

sum(1:10)
sum(c(2,5,6,7,1,2))
```

output:

 55

 23

#### Example of sum function with NA:

sum() function doesn’t give desired output, If NAs are present in the vector. so it has to be handled by using na.rm=TRUE in sum() function

```# sum() function in R for input vector which has NA.

x = c(1.234,2.342,-4.562,5.671,12.345,-14.567,NA)
sum(x,na.rm=TRUE)
```

output:

 2.463

#### Example of sum() function in R dataframe:

Lets create the data frame to demonstrate sum function – sum() in r

```### create the dataframe
Price = c(100,80,80,90,65,70,60,70,25,60,40,35,50,120),
Tax = c(2,4,5,6,2,3,5,1,3,4,5,6,4,3))
```

so the resultant dataframe will be #### sum of a column in R data frame using sum() function : sum() function takes the column name as argument and calculates the sum of that particular column

```# sum() function in R : sum of a column in data frame

```

so the resultant sum of “Price” column will be

output:

 945

#### column wise sum using sum() function:

sum() function is applied to the required column through mapply() function, so that it  calculates the sum of required column as shown below.

```
# sum() function in R : sum of multiple column in data frame

```

so the resultant sum of “Price” and “Tax” columns will be #### Sum of the column by group using sum() function

aggregate() function along with the sum() function calculates the sum of a group. here sum of “Price” column, for “Item_Group” is calculated.

```##### Sum of the column by group
FUN=sum)
```

Item_group has three groups “Dairy”,”Fruit” & “Vegetable”. sum of price for each group is calculated as shown below #### Sum of the column by group  and populate it by using sum() function:

group_by() function along with the sum() function calculates the sum of a group. here sum of “Price” column, for “Item_Group” is calculated and populated across as shown below

```#### sum of the column by group and populate it using dplyr

library(dplyr)

group_by(ITEM_GROUP) %>%
mutate(sum_by_group = sum(Price))
```

Item_group has three groups “Dairy”,”Fruit” & “Vegetable”. sum of price for each group is calculated and populated as shown below #### Row wise sum using sum() function along with dplyr Row wise sum is calculated with the help rowwise() function of dplyr package  and sum() function as shown below

```## row wise sum using dplyr
library(dplyr)

rowwise() %>%
mutate(
Total_price = sum(c(Price,Tax))
)
```

row wise sum of “Price” and “Tax” is calculated and  populated for each row as shown below For further understanding of sum() function in R using dplyr one can refer the dplyr documentation

## Author

• With close to 10 years on Experience in data science and machine learning Have extensively worked on programming languages like R, Python (Pandas), SAS, Pyspark.