I have been encountering the same problem, and although I don't know why it occurs, I have been able to pin down when it occurs, and thus prevent it from happening.
The issue seems to be with adding in a new column, derived from indexing, in a base R data frame vs. in a tibble data frame. Take this example, where you add a new column (age
) to a base R data frame:
base_df <- data.frame(id = c(1:3), name = c("mary", "jill","steve"))
base_df$age[base_df$name == "mary"] <- 47
That works without returning a warning. But when the same is done with a tibble, it throws a warning (and consequently, I think causing the weird, seemingly unprovoked, multiple warning issue):
library(tibble)
tibble_df <- tibble(id = c(1:3), name = c("mary", "jill","steve"))
tibble_df$age[tibble_df$name == "mary"] <- 47
Warning message:
Unknown column 'age'
There are surely better ways of avoiding this, but I have found that first creating a vector of NA
s does the job:
tibble_df$age <- NA
tibble_df$age[tibble_df$name == "mary"] <- 47