the most awesome purrr feature?

purrr_awesome.R

# capturing failure with default values

library(purrr)


# a faulty function 
f <- function(x){
  
  # some nasty error occuring once in a while 
  if( x %% 2 == 0 ){
    stop("HAHA!")
  }
  
  # what should be returned
  return("ok")
}



# lets make f() save again
f_save <- safely(f, otherwise = "error")
f_poss <- possibly(f, otherwise = "error")


# failing 
vapply(1:5, f, "")


# capturing failure with handy defaults
lapply(1:5, f_save)

# processing results and status
f_results <- lapply(1:5, f_save) 

f_results_df <- 
  data.frame(
    value = f_results %>% vapply( function(x){ x$result }, character(1) ),
    error = f_results %>% vapply( function(x){ !is.null(x$error) }, logical(1)),
    error_message = 
      f_results %>% 
        vapply( function(x){tmp <- x$error$message; if(is.null(tmp)){""}else{tmp}}, character(1)),
    stringsAsFactors = (HELLNO <- FALSE)
  )


# Just give me the results - would you!
vapply(1:5, f_poss, "")