Remove all-FALSE columns

remove-false.R

# How to batch-remove columns which are all FALSE in data.table

library(data.table)
dt <- data.table(x = c(TRUE, FALSE, FALSE), 
                 y = c(FALSE, FALSE, FALSE),   # all FALSE
                 z = c(FALSE, FALSE, TRUE), 
                 a = c(FALSE, FALSE, FALSE)   # all FALSE
)
dt
all_false_cols <- apply(dt, MARGIN = 2, function(x){ all(x == FALSE)})
all_false_cols
dt2 <- dt[ , !all_false_cols, with = FALSE]
dt2