count json lines dynamically

Question

I asked this question earlier this morning "here is my JSON file :

[
{
    "Week": "1145",
    "Sev_Logged": "3_major",
    "From": "IN1"
},
{
    "Week": "1145",
    "Sev_Logged": "4_minor",
    "From": "IN1"
},
{
    "Week": "1145",
    "Sev_Logged": "4_minor",
    "From": "IN1"
},
{
    "Week": "1145",
    "Sev_Logged": "4_minor",
    "From": "IN1"
},
{
    "Week": "1145",
    "Sev_Logged": "4_minor",
    "From": "IN1"
},
{
    "Week": "1145",
    "Sev_Logged": "4_minor",
    "From": "IN2"
},
{
    "Week": "1145",
    "Sev_Logged": "3_major",
    "From": "IN2"
},
];

I want to count the "from : IN1" field for each "week", per example for week : 1145 i'd get : 3, and for "From : IN2" i'd get 2

Thanks"

Thank you VDP for your answer, so I did this : My store is now like :

Ext.define('Metrics.store.GraphData', {
extend : 'Ext.data.Store',
model : 'Metrics.model.GraphData',
autoload : true,

proxy : {
    type : 'ajax',
    url : 'data/metrics_data.json',
    reader : {
        type : 'json',
        root : 'data',
        successProperty : 'success'
    }
},
//data : GraphData, //povide inline data or load using proxy
countBy: function(param){
    var count = {};
    this.each(function(item){
        var type = item.get(param);
        if (Ext.isDefined(count[type])){
            count[type]++;
        } else {
            count[type] = 1;
        }                               
    });
    return count;
}
});

And my model :

Ext.define('Metrics.model.GraphData', {
extend: 'Ext.data.Model',
//fields: ['week', 'sev']
fields : [ 
    {name: 'Week',  type: 'int'},
    {name: 'Sev_Logged',   type: 'string'},
    {name: 'From', type: 'string'}
]
});

Since i'm using extjs 4 with MVC model, I have made a controller wich controls the event of a button, right now it looks like this :

launchGraph : function(button){
console.log('clicked the apply button');
var chartStore = this.getGraphDataStore();
chartStore.load({
    callback: this.onGraphDataLoad,
    scope: this,
    console.log(chartStore.countBy("From"))
    });

But when I click the apply button I get this error in my controller :

"Uncaught SyntaxError: Unexpected token . "

And it points to the line :

 "console.log(chartStore.countBy("From"))"

It seems like i have an error in the referencing to my store. Any ideas?

Answer 1

If you are using the array you provide you can just use the mimikomi's answer or a similar ExtJS version of it:

here is a fiddle

function countBy(data, param) {
    var count = {};
    Ext.each(data, function(item){
        var type = item[param];
        if (Ext.isDefined(count[type]))  {
            count[type]++;
        } else {
            count[type] = 1;
        }  
    });
    return count;
}

If you load that json from an external location it's best practice to load it in a store. You define a model, a store and add 'special' functions to your store for example.

Ext.define('Week', {
    extend: 'Ext.data.Model',
    fields: [
        {name: 'Week',  type: 'int'},
        {name: 'Sev_Logged',   type: 'string'},
        {name: 'From', type: 'string'}
    ]
});

var store = Ext.create('Ext.data.Store', {
    model: 'Week',
    data : data, //povide inline data or load using proxy
    countBy: function(param){
        var count = {};
        this.each(function(item){
            var type = item.get(param);
            if (Ext.isDefined(count[type])){
                count[type]++;
            } else {
                count[type] = 1;
            }                               
        });
        return count;
    }
});

var countObject = store.countBy("From");

alert(Ext.encode(countObject));
//chrome developper tools, safari, opera can show us the contents of objects in a log too. IE, FF however only tell us it is an object. (pretty useless)
console.log(countObject);
//you can chose you're favorite notation to retreve the value (but I hope you knew this, it's pretty basic javascript)
console.log(countObject.IN1); 
console.log(countObject['IN2']);

Here is a fiddle.

More info on loading json dynamically into a store via ajax (using a proxy)

Answer 2

If var jsonData is the array resulting from parsing the json shown above, this will give you an object with the counts of each depending on the parameter you use..

function CountBy(parameter) {
  var count = {};
  for (var i = 0; i < jsonData.length; i++) {
  var type = jsonData[i][parameter];
    if (count[type] === undefined)  {
      count[type] = 1;
    } else {
      count[type]++;
    }  
  }
  return count;
}

Result:

CountBy("From") => {"IN1" : 5, "IN2" : 2}
CountBy("Week") => {"1145" : 7}
CountBy("Sev_Logged") => {"3_major": 2, "4_minor": 5}