How to fill NAs with LOCF by factors in data frame, split by country

Question

I have the following data frame (simplified) with the country variable as a factor and the value variable has missing values:

country value
AUT     NA
AUT            


        

Answer 1

A combination of the packages dplyr and imputeTS can do the job.

library(dplyr)
library(imputeTS)
data %>% group_by(country) %>% 
mutate(value = na.locf(value, na.remaining="keep"))   

With the na.remaining parameter of the na.locf function of imputeTS you have additionally the option to choose, what to do with the trailing NAs.

These are the options:

• "keep" - return the series with NAs
• "rm" - remove remaining NAs
• "mean" - replace remaining NAs by overall mean
• "rev" - perform nocb / locf from the reverse direction

By choosing "mean" you would for example get a result with 7 for every GER in the specific example.