Convenience function that allows mutating a subset of rows
mutate_cond(.data, condition, ..., envir = parent.frame())
a tibble with specified rows modified
a tibble
a logical vector for subsetting rows of `.data`
Name-value pairs of expressions to be evaluated by `mutate()`
environment within which expressions should be evaluated
Original code taken from https://stackoverflow.com/questions/34096162/dplyr-mutate-replace-several-columns-on-a-subset-of-rows