Moving sum of a certain window in R

Question

I want to calculate a running sum of the next 5 rows. In this case, on row 1 it will show the sum of numbers from row 2 to row 6. The last 5 rows of the data frame can be filled with NA.

The data looks like this

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And the ideal result would look like

enter image description here

Thank you!

Answer 1

First, please consider to read How to make a great R reproducible example? and add sample data using dput next time.

df <- data.frame(t = c(1,3,5,2,1,3,4,6,7,2,1))

library(zoo)
library(dplyr)

df$V2 <- rollsum(lead(df$t), 5, align = "left", fill = NA)
df

   t V2
1  1 14
2  3 15
3  5 16
4  2 21
5  1 22
6  3 20
7  4 NA
8  6 NA
9  7 NA
10 2 NA
11 1 NA

Answer 2

You can use rollsum from the zoo package.

library(zoo)
rollsum(df$column, 5)

The second argument is the number of lines to sum, here it is five.