Safely apply a function to each row of a data frame.

Easily keep track of inputs and outputs of a function safely applied to each row of a data frame. Output is rectangularized into the original data frame for easy analysis.

pmap_safely(.d, .f)

Arguments

.d	A data frame with the inputs to .f.
.f	A function to apply to each row of .d.

Examples

# a function to apply
calculate_if_positive <- function(a, b){
    if(a < 0 & b < 0) {stop("Both numbers are negative.")}
    else if(a < 0) {stop("Just the first number is negative")}
    else if(b < 0) {stop("Just the second number is negative")}

    list(add = a + b,
         subtract = a - b,
         multiply = a * b,
         divide = a / b)
}
# data frame to apply the function to by row
numbers <- data.frame(a = c(-1, 0, 1, 2),
                      b = c(2, 1, 0, -1),
                      irrelevant = c("minneapolis", "st_paul", "minneapolis", "st_paul"))

# apply
pmap_safely(numbers, calculate_if_positive)
#> Note that the function does not use the following variables: irrelevant
#>    a  b  irrelevant                              error       result
#> 1 -1  2 minneapolis  Just the first number is negative         NULL
#> 2  0  1     st_paul                               <NA>  1, -1, 0, 0
#> 3  1  0 minneapolis                               <NA> 1, 1, 0, Inf
#> 4  2 -1     st_paul Just the second number is negative         NULL