Question

119

Best way to replace missing/undefined values in an array?

rated 0 times [ 125] [ 6] / answers: 1 / hits: 7961 / 10 Years ago, fri, march 14, 2014, 12:00:00

I need to process some arrays that contains undefined values, like the following:

[ 1, 1, 1, 1, 1, , 1, 1 ]

[ 1, , 1, , , 1, 1 ]

[ 1, , , , , 1, 1 ]

What I need to achieve is not a removal of the undefined values, but I need to replace them with zeros.

I tried to use underscore.js to achieve this; without success.

The following is my solution attempt:

binarymap = _.map(binarymap, function(curr){

    // let's replace all undefined with 0s

    if(_.isUndefined(curr)) {

        return 0;

    }

    return curr;

});

Unfortunately, it does not work. underscore.js's function _.map totally ignores undefined values.

Any ideas? Elegant solutions?

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joanneamiyaa

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4 Years ago

answered 10 Years ago johnnyblaynes · Accepted Answer

If you wanted to you could add the function as a mixin for use in an underscore chain. Improvised from here.

_.mixin({

  dothis: function(obj, interceptor, context) {

    return interceptor.call(context, obj);

  }

});



function resetArray(arr) {

  for (var i = 0, l = arr.length; i < l; i++) {

    if (arr[i] === undefined) arr[i] = 0;

  }

  return arr;

}



var arr = [ 1, , , , , 1, 1 ];



_(arr)

  .chain()

  .dothis(resetArray)

  .tap(console.log) // [1, 0, 0, 0, 0, 1, 1]

Fiddle

Edit: actually, there's a simpler way of doing that:

_.mixin({

  resetArray: function (arr) {

    for (var i = 0, l = arr.length; i < l; i++) {

        if (arr[i] === undefined) arr[i] = 0;

    }

    return arr;

  }

});



var arr = [1, , , , , 1, 1];



_(arr)

  .chain()

  .resetArray()

  .tap(console.log)

Fiddle