Sum arrays' columns in AngularJS

Question

I am pretty new to AngularJS (and to development in general). I am trying to create a simple game and I am stuck with one problem.

The user can add words to a list and my script automatically associate 5 random numbers (in a specific range) to every item with the following:

$scope.randomNum = getNum();
function getNum () {
    var arr = [];
    min = 1;
    max = 5;
    for (i=0; i<5; i++) {
        arr.push(Math.floor(Math.random() * (max - min + 1)) + minEffort);
    }
    return arr;
}

I would like to dynamically get the sums of the columns of those arrays. For instance, if the user adds three words:

First
Second
Third

and these words get respectively the following random numbers:

[0,5,2,4,2]
[3,5,1,2,1]
[4,3,4,1,2]

I need to push to the page the total of every column: 7, 13, 7, 7, 5. And I also need to use those totals to run further math.

How can I do that?

EDIT I stumbled upon this filter:

app.filter('sumByKey', function () {
  return function (data, key) {
    if (typeof (data) === 'undefined' || typeof (key) === 'undefined') {
      return 0;
    }

    var sum = 0;
    for (var i = data.length - 1; i >= 0; i--) {
      sum += parseInt(data[i][key]);
    }

    return sum;
  };
});

That allows me to get the sum for a single columns with

{{items|sumByKey: 'randomNum[i]'}}

Can I reiterate it automatically for the total number of columns? Can I store the results in another array for further operations?

marc_s · Accepted Answer · 2024-10-17 07:58:48Z

1

$scope.sums will contain sum of all columns. You can use it further.

$scope.words = [];
$scope.sums = [];
$scope.getNum = function () {
    var arr = [];
    min = 1;
    max = 5;
    for (i = 0; i < 5; i++) {
        arr.push(Math.floor(Math.random() * (max - min + 1)) + minEffort);
    }
    return arr;
};

//add word and associate random number arrays
$scope.add_word = function (word) {
    $scope.words.push({word_text: word, numbers: $scope.getNum()});
};

// give columns sums,no matter what how many rows are
$scope.get_columns_sum = function () {
    angular.forEach($scope.words, function (word, key) {
        angular.forEach(word.numbers, function (number, key) {
            if (isNaN($scope.sums[key])) {
                $scope.sums[key] = number;
            } else {
                $scope.sums[key] = $scope.sums[key] + number;
            }
        });
    });
    console.log($scope.sums);
};

$scope.add_word('first word');
$scope.add_word('second word');
$scope.add_word('third word');
$scope.get_columns_sum();

edited Oct 17, 2024 at 7:58

marc_s

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answered Mar 7, 2015 at 15:37

Mudasser Ajaz

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4 Comments

Mirko G. Over a year ago

Thanks a lot mudasser. I am not sure why I am getting "undefined" for get_colums_sum()... I put my code in JSFiddle, but apparently it is not working at all: jsfiddle.net/nitecorp/n61cmkfg/2 While on my local server everything but the sum is working...

Mudasser Ajaz Over a year ago

@MirkoG. you were missing to define $scope.sums in controller,which was being used in get_col_sum function. Here is plnkr plnkr.co/edit/fDgY0syOUacSXtJVBQlr?p=preview , $scope.sums is array which keeps total of all columns.

Mirko G. Over a year ago

Thanks Mudasser, If I return the sum something weird happens: the first sum looks like the number of the first array are repeated twice, then the sum changes as soon as I type something in the input text field: plnkr.co/edit/ltNwhJupqfWINHc8cl1N?p=preview :(

Mudasser Ajaz Over a year ago

@MirkoG. check now plnkr.co/edit/A7RCdXMUst2pZF8cN6K2?p=preview its working right, i was not making $scope.sums = [] before each new sums cycle.It is fixed now.

Fran Herrero · Accepted Answer · 2015-03-07 16:24:55Z

0

Assuming that every array has the same length (5 elements in this case) you can apply the next algorithm.

array_of_arrays will be an array of the arrays to sum, it means:

var array_to_arrays = [[0,5,2,4,2], [3,5,1,2,1], [4,3,4,1,2]];

function sumCols(array_to_arrays) {
   var sum = 0;
   var sum_cols = [];
   for(var i = 0; i < 5; i++) {
      for(var j = 0; j < array_to_arrays.length; j++) {
         sum += array_to_arrays[j][i];
      }
      sum_cols.push(sum);
      sum = 0;
   }
   return sum_cols;
}

I created a plnkr with a example: http://plnkr.co/edit/0FElcQamh9b7nHbQDMkn?p=preview

edited Mar 7, 2015 at 16:24

answered Mar 7, 2015 at 15:31

Fran Herrero

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2 Comments

Mirko G. Over a year ago

Thank you Fran, how can I make this solution independent from the number of arrays? array_to_array could contain from 0 to N arrays. How do I dynamically get it?

Fran Herrero Over a year ago

The function is independent of array_to_arrays length. The only assumption is that every component must be equal length (five in this case).

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