repply.R

## A short function which is effectively a wrapper around lapply, where the function is reattempted on failure
## a set number of times

repply <- function(X, FUN, ..., .max_retry = 3) {
  
  init <- lapply(X, function(x) try(FUN(x), silent = TRUE), ...)
  
  n <- 1
  
  while(n <= .max_retry) {
    
    errors <- which(sapply(init, class) == "try-error")
    
    if(length(errors) == 0) return(init)
    
    init[errors] <- lapply(X[errors], function(x) try(FUN(x), silent = TRUE), ...)
    
    n <- n + 1
    
  }

  return(init)

}


# Example -----------------------------------------------------------------

error_sometimes <- function(numbers, p = 0.3) {
  
  if(runif(1) < p) stop("error")
  mean(numbers)
  
}

num_list <- 
  list(
    rnorm(100),
    rnorm(100),
    rnorm(100),
    rnorm(100),
    rnorm(100)
  )

repply(X = num_list, error_sometimes)