Transpose 2 strings in an array

Question

I have the following code:

function transposeTwoStrings(arr){
 var stringOne = arr[0];
 var stringTwo = arr[1];

 for (var i = 0; i < arr.length; i++) {
     return (stringOne.charAt(i) + " " + stringTwo.charAt(i));
 }

I am expecting output as follows:

e.g. transposeTwoStrings(['Hello','World']);

should return

H W
e o
l r
l l
o d

However it is only returning the first character at the first index of each string. I am trying to return all characters for both strings.

I initially had a much more verbose solution using if/else and decided to refactor using for loop.

I am stuck as output currently being shown when executed is

H W

haim770 · Accepted Answer · 2017-04-03 19:47:18Z

4

You are retuning in the middle of your loop, which will cause it to only loop once. Also, you're using the wrong object to determine the length.

Try this instead:

function transposeTwoStrings(arr){
    var stringOne = arr[0];
    var stringTwo = arr[1];
    var ret = '';

    for (var i = 0; i < arr[0].length; i++) {
        ret += stringOne.charAt(i) + " " + stringTwo.charAt(i) + '\n\r';
    }

    return ret;
}

answered Apr 3, 2017 at 19:47

haim770

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2 Comments

g01di3l0ck5 Over a year ago

I like this based on where mine already is, but when I add the newline it appends it to the last iteration which does not need a newline after

haim770 Over a year ago

@g01di3l0ck5, You can just change to return ret.trim() or check that i < arr[0].length before appending the \n\r

trincot · Accepted Answer · 2017-04-03 20:02:47Z

2

The return in your loop makes it stop during its first iteration. Once you fix that, you should also change the end condition of your loop as otherwise it will only iterate twice.

But you can do it also using split, map and join like this:

function transposeTwoStrings(arr){
    return arr[0].split('')
                 .map( (a, i) => a + ' ' + arr[1][i] )
                 .join('\n'); 
}

var result = transposeTwoStrings(['Hello','World']);

console.log(result);

Alternative with `replace` callback

function transposeTwoStrings(arr){
    var i = 0;
    return arr[0].replace(/./g, c => c + ' ' + arr[1][i++] + '\n')
}

var result = transposeTwoStrings(['Hello','World']);

console.log(result);

edited Apr 3, 2017 at 20:02

answered Apr 3, 2017 at 19:50

trincot

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Comments

Tony · Accepted Answer · 2017-04-03 20:21:14Z

2

Use one of the strings length as a condition in the for loop:

function transposeTwoStrings(arr){
 var stringOne = arr[0];
 var stringTwo = arr[1];
 var calculatedStr = '';

 var loopCount = 0;

 // CALCULATE LOOP COUNT
 if(stringOne.length > stringTwo.length){
     loopCount = stringTwo.length;
 }else{
     loopCount = stringOne.length;
 }

 for (var i = 0; i < loopCount; i++) {
     calculatedStr += stringOne.charAt(i) + " " + stringTwo.charAt(i));
 }

 // ADD REMAINING CHARACTERS TO STRING RESULT IF SIZE IS DIFFERENT
 if(stringOne.length > loopCount){

     calculatedStr += stringOne.substring(loopCount);

 }
 if(stringTwo.length > loopCount){

     calculatedStr += stringTwo.substring(loopCount);

 }

 return calculatedStr;

}

edited Apr 3, 2017 at 20:21

answered Apr 3, 2017 at 19:44

Tony

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4 Comments

alexanderbird Over a year ago

You'll also want to consider what happens if the strings aren't the same length

g01di3l0ck5 Over a year ago

That is actually a requirement. for example my tests are (['Hello','World']) (['joey','louise']) (['a','cat']) (['cat','']) (['!a!a!','?b?b'])

Tony Over a year ago

@g01di3l0ck5 if the strings are not the same length I suggest you use the smaller of the strings. I edited the answer to show this.

Tony Over a year ago

@g01di3l0ck5 I edited the answer to add remaining characters to the result if they were different in size. This should work for all those test cases.

Nelson Teixeira · Accepted Answer · 2017-04-03 19:53:53Z

1

this will do the trick:

var strgs = ['Hello','World'];
var res = strgs[0].split('').map((l, ix)=>[l, strgs[1][ix] || '']);
console.log(res);

if you prefer concatenated strings:

var strgs = ['Hello','World'];
var res = strgs[0].split('').map((l, ix)=>l + ' ' + strgs[1][ix] || '')
console.log(res);

printing string to console:

var strgs = ['Hello','World'];
var res = strgs[0].split('').map((l, ix)=>l + ' ' + strgs[1][ix] || '')
res.forEach((e)=>console.log(e));

In case of different size strings the first will define the length and the second element will be '' if the first element don't exist.

edited Apr 3, 2017 at 19:53

answered Apr 3, 2017 at 19:48

Nelson Teixeira

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Comments

Nina Scholz · Accepted Answer · 2017-04-03 21:16:10Z

1

You could use the maximal length of the strings and respect empty places.

function transposeTwoStrings(array){
    var i, length = array.reduce(function (r, a) { return Math.max(r, a.length); }, 0),
        result = [];

    for (i = 0; i < length; i++) {
        result.push(array.map(function (a) { return a[i] || ' '; }).join(' '));
    }
    return result;
}

console.log(transposeTwoStrings(['Hello', 'World']).join('\n'));
console.log(transposeTwoStrings(['This', 'is', 'a', 'test']).join('\n'));

.as-console-wrapper { max-height: 100% !important; top: 0; }

answered Apr 3, 2017 at 21:16

Nina Scholz

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Comments

mandrei100 · Accepted Answer · 2019-06-14 22:30:49Z

0

Give this a shot:

function transposeTwoStrings(arr) {
  var array = [];
  for (var i = 0; i < arr[0].length; i++) {
    array.push(arr[0][i] + " "+ arr[1][i]);
  }
  return array.join('\n');
}

console.log(transposeTwoStrings(['Hello','World']));

answered Jun 14, 2019 at 22:30

mandrei100

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