R autofill blanks in variable until next value

Question

I want to auto-populate a variable in R with a value until the next value is reached in the column.

I want to turn this:

Into:

Possible duplicate of [Replacing NAs with latest non-NA value](http://stackoverflow.com/questions/7735647/replacing-nas-with-latest-non-na-value) — mtoto, Mar 13 '17 at 17:41

score 5 · Answer 1 · answered Mar 14 '17 at 03:12

5

You can do this with tidyr::fill

library(tidyr)
mydf <- data.frame(X = c('a', NA, NA, 'b', NA, NA, 'c'), Y =rep(1,7))
mydf %>% fill(X)

  X Y
1 a 1
2 a 1
3 a 1
4 b 1
5 b 1
6 b 1
7 c 1

answered Mar 14 '17 at 03:12

A Toll

647
7
15

For those that dislike the tidyverse pipe syntax this is also an option: `mydf_filled<- fill_(mydf,c("X"))` – fileunderwater Feb 13 '18 at 22:29

Sandipan Dey · Accepted Answer · 2017-03-13T19:19:24.923

We could try na.locf from zoo:

df <- read.csv(text='X,  Y       
             a, 1
              , 1
              , 1
             b, 1
              , 1
              , 1
             c, 1', header=TRUE, stringsAsFactors=FALSE)

df # input
#                   X Y
#1                  a 1
#2                    1
#3                    1
#4                  b 1
#5                    1
#6                    1
#7                  c 1

library(zoo)
df$X <- gsub('\\s+', '', df$X)  # replace multiple spaces by blanks
df$X[df$X == ''] <- NA  # replace blanks by NAs
df$X <- na.locf(df$X)
df
#  X Y
#1 a 1
#2 a 1
#3 a 1
#4 b 1
#5 b 1
#6 b 1
#7 c 1

yes... you can also add `fromLast = TRUE ` to fill from the bottom up! — Dan Slone, Mar 13 '17 at 18:57

R autofill blanks in variable until next value

2 Answers2

Linked