CODEWITHSUNDEEP
r
Erik Hahn
Erik Hahn

Reputation: 53

How to replace NA value of one column with the value coming after that column?

Here is some sample data:

dat <- data.frame(col0 = c(1, 1, 1, 2, 2, 2, 3, 3, 3), 
       col1 = c(NA, 100, 100, NA, 200, 200, NA, 300, 300),
       col2 = c(1, 2, 3, 1, 2, 3, 1, 2, 3))

I would like to change any NA value in col1 when col2 = 1, with the value that succeeds the NA in col1.

The best I can figure out is

dat <- dat %>% 
       mutate(col1 = replace(col1, which(is.na(col1) & 
              col2 == 1), 100))

But I couldn't figure out how to get the next value of col1...

Ideally, the solution would use tidyverse.

My actual dataset is quite large so a replacing NA in col1 with c(100, 200, 300) would not be an efficient way to proceed.

Upvotes: 2

Views: 78

Answers (2)

akrun
akrun

Reputation: 887048

An option using na.locf

library(zoo)
dat$col1 <- na.locf(dat$col1, fromLast = TRUE)
dat$col1
#[1] 100 100 100 200 200 200 300 300 300

Upvotes: 1

www
www

Reputation: 39154

We can use fill from the tidyr package.

library(tidyr)

dat2 <- fill(dat, col1, .direction = "up")
dat2
#   col0 col1 col2
# 1    1  100    1
# 2    1  100    2
# 3    1  100    3
# 4    2  200    1
# 5    2  200    2
# 6    2  200    3
# 7    3  300    1
# 8    3  300    2
# 9    3  300    3

Upvotes: 2

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