Vectorized conditional outputs in R (maybe using purrr)?

Question

I am trying to create vectorized conditional outputs of a data frame.

Suppose I have the dataframe:

data <- data.frame(a = c(5, 3, 9, 5),
                   b = c(1, 2, 3, 4),
                   c = c(5, 3, 9, 5),
                   d = c(5, 3, 9, 5))

And the threshold:

threshold <- c(a1 = 4, b1 = 2, c1 = 8, d1 = 2)

What I want is a new dataset that indicates whether each value of a is greater than or equal to the corresponding value in the threshold vector (a1), each value of b is greater than or equal to the corresponding value in the threshold vector (b1), etc.

So the desired output would be:

desired_data <- data.frame(a = c(1, 0, 1, 1),
                           b = c(0, 1, 1, 1),
                           c = c(0, 0, 1, 0),
                           d = c(1, 1, 1, 1))

I want to do this as simply as possible, ideally using a purrr function.

Here is a wrong attempt:

desired_data <- map(data >= threshold)

I feel like map2 might be promising, and have checked the documentation (e.g., here and here) but I can't seem to get the syntax for conditional outputs based on mapping.

Thank you!

Answer 1

You have the idea with map2(): since a data frame is a list of column, you can loop on the columns. The small difficulty is to put everything in a data frame at the end, it's done automatically if you use map2_df().

map2_df(threshold, data, ~ .y >= .x)

And if you want these logical values to be converted to integers:

1L * map2_df(threshold, data, ~ .y >= .x)
#   a1 b1 c1 d1
# 1  1  0  0  1
# 2  0  0  0  1
# 3  1  1  1  1
# 4  1  1  0  1