CODEWITHSUNDEEP
rimputation
lele
lele

Reputation: 47

Add missing value in column according to value of previous or next row in R

I have some longitudinal data and need to impute missing values by some rules:

  1. If a person’s first follow-up data is missing, then add the value of the next row;

  2. If a person's non-first follow-up data is missing, then add the value of the previous row;

  3. If multiple consecutive follow-up data are missing, then add the value of the previous non-missing row.

Here is an example,

dat<-data.frame(id=c(1,1,1,1,1,1,2,2,2,2,2,2,2,3,3,3,3,3,3,3,3),b6=c(NA,1,1,1,1,1,1,1,1,1,NA,3,NA,NA,5,5,5,5,3,NA,NA))
dat_imputed<-data.frame(id=c(1,1,1,1,1,1,2,2,2,2,2,2,2,3,3,3,3,3,3,3,3),b6=c(1,1,1,1,1,1,1,1,1,1,1,3,3,5,5,5,5,5,3,3,3))

Thanks for any suggestions!

Upvotes: 1

Views: 816

Answers (2)

Iaroslav Domin
Iaroslav Domin

Reputation: 2718

Group by id, fill values downwards, then fill upwards. I think this is what you need.

library(dplyr)
library(tidyr)

res <- dat %>% 
  group_by(id) %>% 
  fill(b6, .direction = "down") %>% 
  fill(b6, .direction = "up")

Upvotes: 1

GKi
GKi

Reputation: 39717

You can use approxfun to add missing values inside ave for grouping like:

dat$b6 <- ave(dat$b6, dat$id, FUN=function(x)
   approxfun(x, method = "constant", rule=2)(seq_along(x)))
identical(dat, dat_imputed)
#[1] TRUE

Upvotes: 1

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