CODEWITHSUNDEEP
javascriptarraysfor-loop
Rayan Suryadikara
Rayan Suryadikara

Reputation: 247

JavaScript array 2 dimension for loop

I want to define a two dimensional array object with for loop... my problem I think my object didn't really get processed, here's the code :

var newLoc = [];

var index;

for (index = 0, i < locations.length; i++){
                if(i == 0) {
                    newLoc[i][0] = locations[i][1];
                    newLoc[i][1] = locations[i][2];
                }
                else {
                    if(locations[i][8] == locations[i-1][8]){
                        newLoc[i-1][0] = (locations[i][1] + locations[i-1][1])/2;
                        newLoc[i-1][1] = (locations[i][2] + locations[i-2][1])/2;    
                    }                            
                    else{
                        newLoc[i][0] = locations[i][1];
                        newLoc[i][1] = locations[i][2];
                    }
                }
            }

locations array itself is the old array which store the data for new array (newLoc). locations' data are existing which are coordinate latitude and longitude. I suppose there is something wrong with my for loop form or how I declare newLoc 2 dimension array, but I still don't know how to fix it. Any help appreciated.

Upvotes: 1

Views: 241

Answers (4)

masud_moni
masud_moni

Reputation: 1248

There are some things you can do with your code for optimization. First you have to initialize your loop correctly. then inside the loop, it is better to assign the value statically rather checking it every time for only one implementation. This should optimize your code. The old location posting could make the following code more optimized. 

var newLoc = [];

if(locations.length > 0){
    for(var j = 0; j < 1; ++j) {
        newLoc[j] = [ ];

        newLoc[j][0] = locations[0][1]; 
        newLoc[j][1] = locations[0][2];

    }

}

for (var i = 1, i < locations.length; i++){

    if(locations[i][8] == locations[i-1][8]){
        newLoc[i-1][0] = (locations[i][1] + locations[i-1][1])/2;
        newLoc[i-1][1] = (locations[i][2] + locations[i-2][1])/2;    
    }                            
    else{
        newLoc[i][0] = locations[i][1];
        newLoc[i][1] = locations[i][2];
    }                
}

Upvotes: 2

Fernando Farias
Fernando Farias

Reputation: 196

You are initializing a one-dimensional array, so, when you iterate over the loop, your javascript code will probably you break.

Try to initialize using this way:

var newLoc = new Array(locations.length).fill(locations.length);

Array Doc: https://developer.mozilla.org/pt-BR/docs/Web/JavaScript/Reference/Global_Objects/Array

Upvotes: 0

mrid
mrid

Reputation: 5796

One thing I noticed, in your for loop, you have written 

for (index = 0, i < locations.length; i++)

instead of 

for (index = 0; i < locations.length; i++)

Note the ;

So, in all the loop should be 

for (index = 0; i < locations.length; i++){
            if(i == 0) {
                newLoc[i][0] = locations[i][1];
                newLoc[i][1] = locations[i][2];
            }
            else {
                if(locations[i][8] == locations[i-1][8]){
                    newLoc[i-1][0] = (locations[i][1] + locations[i-1][1])/2;
                    newLoc[i-1][1] = (locations[i][2] + locations[i-2][1])/2;    
                }                            
                else{
                    newLoc[i][0] = locations[i][1];
                    newLoc[i][1] = locations[i][2];
                }
            }
        }

Upvotes: 0

Ezkin
Ezkin

Reputation: 101

I think the issue is that newLoc is always a 1 dimentionnal array and you declare 'index' in your for loop but use 'i' in the body

var newLoc = [];

// loop with 
for (var i = 0; i < locations.length; i++){
    //Create the second dimention
    newLoc[i] = [];
            if(i == 0) {
                    ...

Upvotes: 1

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