# How to Calculate Cumulative Sums in R (With Examples)

You can use the cumsum() function from base R to easily calculate the cumulative sum of a vector of numeric values.

This tutorial explains how to use this function to calculate the cumulative sum of a vector along with how to visualize a cumulative sum.

### How to Calculate a Cumulative Sum in R

The following code shows how to calculate the cumulative sum of sales for a given company over the course of 15 sales quarters:

```#create dataset
data <- data.frame(quarter=1:15,
sales=c(1, 2, 2, 5, 4, 7, 5, 7, 6, 8, 5, 9, 11, 12, 4))

#create new column in dataset that contains cumulative sales
data\$cum_sales <- cumsum(data\$sales)

#view dataset
data

quarter sales cum_sales
1        1     1         1
2        2     2         3
3        3     2         5
4        4     5        10
5        5     4        14
6        6     7        21
7        7     5        26
8        8     7        33
9        9     6        39
10      10     8        47
11      11     5        52
12      12     9        61
13      13    11        72
14      14    12        84
15      15     4        88
```

The values shown in the cum_sales column represent the total sales up to and including that quarter. For example, the cumulative sales in quarter 5 are calculated as: 1+2+2+5+4 = 14.

### How to Visualize a Cumulative Sum in R

Once we’ve calculated the cumulative sales, we can create a simple line chart in base R to visualize the cumulative sales by quarter:

```plot(data\$cum_sales, type='l', xlab='Quarter', ylab='Cumulative Sales')
``` Alternatively, we can use the R visualization library ggplot2 to create the same line chart:

```library(ggplot2)

ggplot(data, aes(x=quarter, y=cum_sales)) +
geom_line() +
labs(x='Quarter', y='Cumulative Sales')``` 