Rectangularise a set of list columns of different lengths

rectangularise.R

# originally written at
# https://community.rstudio.com/t/unlist-columns-with-lists-of-different-length/
# with grateful acknowledgement of those who worked it out before me :-)

## improved (well, single pipe) version, to summarise values in a df into a summary table
rectangularise <- function(df) {
  df %>%
    purrr::map(unique) %>%
    purrr::map(sort) %>%
    purrr::map(~ `length<-`(., max(lengths(map(df, ~ unique(.)))))) %>%
    dplyr::bind_cols()
}


## rectangularise with added count columns (sorted)
###################################################

# helper
add_counts <- function(df) {
  df %>%
    dplyr::filter(!is.na(value)) %>%
    dplyr::add_count(value, name = "count", sort = TRUE) %>%
    dplyr::distinct()
}

rectangularise_with_counts <- function(df) {
  col_names <- unlist(
    map(colnames(df), ~ c(., paste0("count_", .)))
  )
  out <- df %>%
    purrr::map(~.) %>% # makes a list of all df columns

    # need to enframe so add_count can work
    purrr::map(~ tibble::enframe(., name = NULL)) %>%
    purrr::map(~ add_counts(.)) %>%
  
    # turn into a flat list  
    purrr::flatten()

  # can't manage to get it into a single pipeline :-/
  out %>%
    map(~ `length<-`(., max(lengths(out)))) %>%
    bind_cols() %>%
    magrittr::set_colnames(col_names)
}



## original version (designed to deal with a tbl with nested lists)
###################################################################
rectangularise <- function(df) {
  max_len <- df %>%
    purrr::map(unlist) %>%
    lengths() %>%
    max()

  df %>%
    purrr::map(unlist) %>%
    purrr::map(~ `length<-`(., max_len)) %>%
    bind_cols()
}