We have code that recently started to give the following warnings whenever we subset a grouped dataframe that results in zero rows. I understand what 'Factor x
contains implicit NA' refers to, and understand that I could use fct_explicit_na to fix the warning; however, this doesnt seem correct to report it in the situation of zero rows (as opposed to actually having NAs). I only see this with grouped dataframes. See this example:
library(dplyr)
#Create DF:
test <- data.frame(x = factor(c('A', 'B')))
#Group by make grouped_df:
test <- test %>% group_by(x)
#Subset, resulting in zero rows:
ss <- test[test$x == 'C',]
# Warning message:
# Factor `x` contains implicit NA, consider using `forcats::fct_explicit_na`
I am using dplyr_0.8.3. Thanks for any comments.