R: replacing NAs in a data.frame with values in the same position in another dataframe

Question

I have a dataframe with some NA values:

dfa <- data.frame(a=c(1,NA,3,4,5,NA),b=c(1,5,NA,NA,8,9),c=c(7,NA,NA,NA,2,NA))
dfa

I would like t

Answer 1

In the tidyverse, you can use purrr::map2_df, which is a strictly bivariate version of mapply that simplifies to a data.frame, and dplyr::coalesce, which replaces NA values in its first argument with the corresponding ones in the second.

library(tidyverse)

dfrepair %>% 
    mutate_all(as.numeric) %>%    # coalesce is strict about types
    map2_df(dfa, ., coalesce)

## # A tibble: 6 × 3
##       a     b     c
##     
## 1     1     1     7
## 2     3     5     7
## 3     3     4     6
## 4     4     3     5
## 5     5     8     2
## 6     7     9     3