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I am trying to create a multi dimensional array based off of the calculations of another 3D array.

Input array is in format [shift, start Num, end num]

I should be clear the "," is just for visual purposes. I need each value in its own array location i.e. [value1]=location 0,0 [value2]=location 0,1 [value3]=location 0,2 etc.

Example:

aInput looks like this
[0,1,5]
[1,1,3]
[2,1,2]

aOutput should look like this
[1,1,1]
[1,1,2]
[1,2,1]
[1,2,2]
[1,3,1]
[1,3,2]
[2,1,1]
[2,1,2]
[2,2,1]
[2,2,2]
[2,3,1]
[2,3,2]
[1,3,2]
[3,1,1]
[3,1,2]
[3,2,1]
[3,2,2]
[3,3,1]
[3,3,2]
[etc]

It needs to increase the number of items in the array based on the shift. i.e 0 = shift would be 1 column, shift = 1 would be 2 columns, shift = 3 would be 3 columns, and so on. This is what I have so far, but I can not figure out how to make it calculate for anything with a shift.

var aInput = new Array();
aInput[0] = new Array("0", "1","5");
aInput[1] = new Array("1", "1","3");
aInput[2] = new Array("2", "1","2");

for (var x=0; x < aInput[x].length; x++){
    //Calculate out number
    if (aInput[x][0] == 0){ // Im sure this should be a loop of some sort, just not sure how to do it
        var i=Number(aInput[x][1]);
        while (i <= Number(aInput[x][2])){
            //Write to output array
            aOutput.push(i);
            i++;
        }
    }
}

Thanks in advance for any help, I'm really stumped on this one.

share|improve this question
Sorry, could you please be more specific about the calculation algorithm? I can't really spot a pattern, and I don't get your input and output formats. Is it an example of three different inputs? Or is that actually an array of three arrays? What is [etc], I don't expect an infinite array? – Bergi Apr 29 at 23:22
Your question mentions a 3D array. Your input looks like a 2D array. – Barmar Apr 29 at 23:24
**I should be clear the "," is just for visual purposes. I need each value in its own array location i.e. [value1]=location 0,0 [value2]=location 0,1 [value3]=location 0,2 etc. – user2300933 Apr 29 at 23:26
Is myArr[1] supposed to be aInput[1]? Do you mean aInput = [[0, 1, 5], [1, 1, 3], [2, 1, 2]];? – Barmar Apr 29 at 23:27
Input Format is [shift] [start number] [end number] – user2300933 Apr 29 at 23:27
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2 Answers

up vote 0 down vote accepted 
var aInput = new Array();
aInput[0] = new Array("0", "1", "5");
aInput[1] = new Array("1", "1", "3");
aInput[2] = new Array("2", "1", "2");

var input_indexed = [],
    elem = []; // elem holds the row to be added to the output

// Get aInput[] into a more useful arrangement
for (var i = 0; i < aInput.length; i++) {
    // Save the range of each column
    input_indexed[parseInt(aInput[i][0])] = {
        start: parseInt(aInput[i][1]),
        end: parseInt(aInput[i][2])
    };
    // Initialize elem with the start value of each column
    elem[aInput[i][0]] = parseInt(aInput[i][1]);
}

// Produce the output
aOutput = [];
done = false;
while (!done) {
    aOutput.push(elem.slice(0)); // push a copy of elem into result
    for (i = elem.length - 1;; i--) { // Increment elements from right to left
        if (i == -1) { // We've run out of columns
            done = true;
            break;
        }
        elem[i]++; // Increment the current column
        if (elem[i] <= input_indexed[i].end) {
            // If it doesn't overflow, we're done
            break;
        }
        // When it overflows, return to start value and loop around to next column
        elem[i] = input_indexed[i].start;
    }
}

FIDDLE

share|improve this answer
This works great! Thank you so much for your help. I am just trying to see how you did it exactly. You are breaking the input array into two separate arrays? I'm a little confused there. Sorry fairly new to JavaScript, if you do not have time to explain I understand and will just study this code more. – user2300933 Apr 30 at 0:17
The original input had the column numbers as array elements. Since we need to look up the start and end values by column, I rearranged it into a new array where the columns are the indexes, and the start/end values are in the values. This is the input_indexed array. – Barmar Apr 30 at 0:19
This isn't even Javascript-specific. I would do the same thing in PHP, Perl, C, etc. – Barmar Apr 30 at 0:21
Yes, I was unaware you could index like that. That will help a lot in the future. So then if I am following correctly you are creating the range using the element array and then pushing that whole array into the aOutput? – user2300933 Apr 30 at 0:28
I've added more comments to explain what it's doing. – Barmar Apr 30 at 0:35
show 10 more comments
up vote 0 down vote 
var aOutput = [];
for (var i in aInput) {
    var y = parseInt(aInput[i][1])
    for (var x = y; x <= parseInt(aInput[i][2]); x++) {
        aOutput.push([i, y, x]);
    }
}
share|improve this answer
1  
for (var i in aInput) is for objects, not arrays. – Barmar Apr 29 at 23:22
1  
there is no difference... it will work – monkeyinsight Apr 29 at 23:31
This looks like it is limited to 3 items across. I need something where the number of items across will expand based on how high the shift number is. – user2300933 Apr 29 at 23:55

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