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# stri_list2matrix: Convert a List to a Character Matrix

## Description

This function converts a given list of atomic vectors to a character matrix.

## Usage

    stri_list2matrix(
      x,
      byrow = FALSE,
      fill = NA_character_,
      n_min = 0,
      by_row = byrow
    )

## Arguments

`x` | a list of atomic vectors
`byrow` | a single logical value; should the resulting matrix be transposed?
`fill` | a single string, see Details
`n_min` | a single integer value; minimal number of rows (`byrow==FALSE`) or columns (otherwise) in the resulting matrix
`by_row` | alias of `byrow`

## Details

This function is similar to the built-in `simplify2array` function. However, it always returns a character matrix, even if each element in `x` is of length 1 or if elements in `x` are not of the same lengths. Moreover, the elements in `x` are always coerced to character vectors.

If `byrow` is `FALSE`, then a matrix with `length(x)` columns is returned. The number of rows is the length of the longest vector in `x`, but no less than `n_min`. Basically, we have `result[i,j] == x[[j]][i]` if `i <= length(x[[j]])` and `result[i,j] == fill` otherwise, see Examples.

If `byrow` is `TRUE`, then the resulting matrix is a transposition of the above-described one.

This function may be useful, e.g., in connection with `stri_split` and `stri_extract_all`.

## Value

Returns a character matrix.

## Author(s)

Marek Gagolewski and other contributors

## See Also

The official online manual of stringi at https://stringi.gagolewski.com/

Gagolewski M., stringi: Fast and portable character string processing in R, Journal of Statistical Software 103(2), 2022, 1-59, doi:10.18637/jss.v103.i02

Other utils: `stri_na2empty()`, `stri_remove_empty()`, `stri_replace_na()`

## Examples

    simplify2array(list(c('a', 'b'), c('c', 'd'), c('e', 'f')))
    ##      [,1] [,2] [,3]
    ## [1,] "a"  "c"  "e"
    ## [2,] "b"  "d"  "f"
    stri_list2matrix(list(c('a', 'b'), c('c', 'd'), c('e', 'f')))
    ##      [,1] [,2] [,3]
    ## [1,] "a"  "c"  "e"
    ## [2,] "b"  "d"  "f"
    stri_list2matrix(list(c('a', 'b'), c('c', 'd'), c('e', 'f')), byrow=TRUE)
    ##      [,1] [,2]
    ## [1,] "a"  "b"
    ## [2,] "c"  "d"
    ## [3,] "e"  "f"
    simplify2array(list('a', c('b', 'c')))
    ## [[1]]
    ## [1] "a"
    ##
    ## [[2]]
    ## [1] "b" "c"
    stri_list2matrix(list('a', c('b', 'c')))
    ##      [,1] [,2]
    ## [1,] "a"  "b"
    ## [2,] NA   "c"
    stri_list2matrix(list('a', c('b', 'c')), fill='')
    ##      [,1] [,2]
    ## [1,] "a"  "b"
    ## [2,] ""   "c"
    stri_list2matrix(list('a', c('b', 'c')), fill='', n_min=5)
    ##      [,1] [,2]
    ## [1,] "a"  "b"
    ## [2,] ""   "c"
    ## [3,] ""   ""
    ## [4,] ""   ""
    ## [5,] ""   ""