Fill NAs when you have zeros in your dataset

Suppose you have the following dataframe:

df <- data.frame(year=c(rep(2010,12),rep(2011,12),rep(2012,12)),
                country=c(rep("DEU",4),rep("ITA",4),rep("USA",4),
                          rep("DEU",4),rep("ITA",4),rep("USA",4),
                          rep("DEU",4),rep("ITA",4),rep("USA",4)),
                industry=c(rep(1:4,9)),
                stock1=c(rep(0,24),0,0,2,4,1,0,1,2,3,3,3,5),
                stock2=c(rep(0,24),0,3,3,4,5,0,1,1,2,2,2,5))

and you want to get the following outcome:

df2 <- data.frame(year=c(rep(2010,12),rep(2011,12),rep(2012,12)),
                 country=c(rep("DEU",4),rep("ITA",4),rep("USA",4),
                           rep("DEU",4),rep("ITA",4),rep("USA",4),
                           rep("DEU",4),rep("ITA",4),rep("USA",4)),
                 industry=c(rep(1:4,9)),
                 stock1=c(rep(NA,24),0,0,2,4,1,0,1,2,3,3,3,5),
                 stock2=c(rep(NA,24),0,3,3,4,5,0,1,1,2,2,2,5))

The concept is that if, for a particular year, a specific country reports zeros in stock2 across ALL industries, then those zeros should be replaced with NAs (Not Available) in both stock1 and stock2. My attempt below

library(dplyr)
df2 = df %>%
  group_by(country, year, industry) %>%
  mutate(
    stock1 = ifelse(all(stock2 == 0), NA, stock1),
    stock2 = ifelse(all(stock2 == 0), NA, stock2)
  )

Thanks!

>Solution :

You can try this approach:

df %>% 
  mutate(
    ind = all(stock2==0),
    across(stock1:stock2, ~if_else(ind, NA,.)),
    .by = c(year, country)) %>% select(-ind)

To avoid the temporary ind column (used to ensure if_else() TRUE and FALSE have same length, you can use case_when() as a shortcut:

mutate(
  df,
  across(stock1:stock2, ~case_when(all(stock2==0)==F~.)),
  .by = c(year, country)
)

Borrowing @shaun_m excellent little trick, you can also use if_else() by setting FALSE to 1, and multiplying:

mutate(
  df,
  mutate(across(stock1:stock2, ~if_else(all(stock2==0), NA,1)*.),
  .by = c(year, country)
)

All give same output