transpose.js•1.1 kB
var _curry1 = require('./internal/_curry1');
/**
* Transposes the rows and columns of a 2D list.
* When passed a list of `n` lists of length `x`,
* returns a list of `x` lists of length `n`.
*
*
* @func
* @memberOf R
* @since v0.19.0
* @category List
* @sig [[a]] -> [[a]]
* @param {Array} list A 2D list
* @return {Array} A 2D list
* @example
*
* R.transpose([[1, 'a'], [2, 'b'], [3, 'c']]) //=> [[1, 2, 3], ['a', 'b', 'c']]
* R.transpose([[1, 2, 3], ['a', 'b', 'c']]) //=> [[1, 'a'], [2, 'b'], [3, 'c']]
*
* If some of the rows are shorter than the following rows, their elements are skipped:
*
* R.transpose([[10, 11], [20], [], [30, 31, 32]]) //=> [[10, 20, 30], [11, 31], [32]]
*/
module.exports = _curry1(function transpose(outerlist) {
var i = 0;
var result = [];
while (i < outerlist.length) {
var innerlist = outerlist[i];
var j = 0;
while (j < innerlist.length) {
if (typeof result[j] === 'undefined') {
result[j] = [];
}
result[j].push(innerlist[j]);
j += 1;
}
i += 1;
}
return result;
});