loop to create array of arrays of same-length strings - arrays

Question

I'm trying to create an array of arrays that are grouped according to their lengths (strings), such that the array below:
var testA = ["carts","carts","cars","cars","ca","ca", "ca","a","a","a","a"];
would become:
var sortedArrays = [["carts","carts"], ["cars","cars"],["ca","ca","ca"], ["a","a","a","a"]]
I am currently trying the loop below but simply cannot get this to work. I know it'll be something simple, but I've spent so long trying to complete this with no that it's proving incredibly frustrating.
var testA = ["carts","carts","cars","cars","ca","ca", "ca","a","a","a","a"];
var sortedArrays = [];
for(i=0; i < testA.length; i++){
longestWord = 0;
wordHolder = []
wordHolder.push(testA[i])
if (testA[i].length > longestWord){
longestWord = testA[i].length
wordHolder.push(testA[i])
}
sortedArrays.push(wordHolder)
}
Any help will be greatly appreciated

Answer 1

What about the following code (Swift, but it should be easy to reformulate it in other languages):
let testA = ["carts","carts","cars","cars","ca","ca", "ca","a","a","a","a"]
var maxLength = 0
for string in testA {
if string.count > maxLength { maxLength = string.count }
}
var sortedArrays: [[String]] = []
for nextLength in 0 ... maxLength {
let invertedLength = maxLength - nextLength
let nextArray = testA.filter { $0.count == invertedLength }
sortedArrays.append(nextArray)
}
This code creates also empty arrays, which can of course easily be skipped.
The question, of course, is what your requirements are. The code above is compact, but it is not fast for large arrays...
For large arrays, it would be better, first to sort testA, and then to extract the elements.

Answer 2

Sticking with java script, I was able to do the following. My assumption is the words are already sorted descending by length and that there is only one word of each length. That's based on what you were doing. I think what was going on is that too much was getting initialized or reset each time through the loop.
var testA = ["carts", "carts", "cars", "cars", "ca", "ca", "ca", "a", "a", "a", "a"];
var sortedArrays = [];
var wordHolder = []; // took outside loop to ensure initialized
var curLength = testA[0].length;// assuming here that testA not empty
for (var i = 0; i < testA.length; i++) {
if (testA[i].length === curLength) { // more of the same
wordHolder.push(testA[i]);
} else { // new block starts
curLength = testA[i].length;
sortedArrays.push(wordHolder);
// alert (wordHolder)
// alert (sortedArrays)
wordHolder = [];
wordHolder.push(testA[i]);
}
}
sortedArrays.push(wordHolder);// add the last one