Looping through two different sized arrays while repeating array 1 values

Question

Hi I an new to programming and am experiencing looping problems. I have two arrays :

colour = ['red','blue','green','orange'];
rows = [1,2,3,4,5,6,7,8,9,10,11...];

I want to have each row element pair with a colour from the colour array, for example starting

rows[0]=>colours[0],
rows[1]=>colours[1],
rows[2]=>colours[2],
rows[3]=>colours[3],
rows[4]=>colours[0],
rows[5]=>colours[1],.....

I basically want to start iterating over the colours once they runout

rows.forEach(function (v, i) { rows[i] = colour[i%4]; });

Paulo R.
– Paulo R.

2013-01-28 21:59:21 +00:00
Commented Jan 28, 2013 at 21:59 — Paulo R.
– Paulo R., Commented Jan 28, 2013 at 21:59

zzzzBov · Accepted Answer · 2013-01-28 21:50:39Z

4

Probably something along the lines of this:

var i,
    rowCount,
    colour,
    rows;
colour = ['red', 'blue', 'green', 'orange'];
rows = [];
rowCount = 20;
for (i = 0; i < rowCount; i++) {
    rows[i] = colour[i % colour.length];
}

The key to this working is the modulus operator (remainder after division). i % color.length is the remainder of i divided by color.length, which relates to the indices of colour.

answered Jan 28, 2013 at 21:50

zzzzBov

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4 Comments

Elliot Bonneville Over a year ago

I had that exact same answer but saw yours as I was about to submit mine... kudos for the speedy answer.

question Over a year ago

You could probably use i < rows.length instead of rowCount.

zzzzBov Over a year ago

@ArthurMigdal, I considered that, but as rows was being overwritten, it seemed more likely that the length was coming in as an external input.

user2019692 Over a year ago

Thanks a million, it worked like a charm. Everyday is a school day :)

Dan Dinu · Accepted Answer · 2013-01-28 21:49:46Z

0

You could iterate thorugh all rows and assign colors in order. When the collor array is done just reset its index.

    var colorIndex = 0;
    for (var i=0; i<rows.length; ++i)
     {
         row[i] = colours[j]; //use the color for the current row
         j++;
         if (j == colours.length) //when you reached the last colour 
          {
              j = 0; //reset colour index.
          }
    }

answered Jan 28, 2013 at 21:49

Dan Dinu

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