CODEWITHSUNDEEP
javascriptjsond3.jsmean
user1386906
user1386906

Reputation: 1179

Calculate mean json with d3.js

I have got a json file like so: 

[
 {"id":1,"sex":"Female","programming":5, "project":7}, 
 {"id":2,"sex":"Male","programming":8, "project":4}, 
 {"id":3,"sex":"Female","programming":5, "project":6}, 
 {"id":4,"sex":"Male","programming":4, "project":7} 
]

I want to calculate the mean of the value's of programming with D3 js I can get the total mean of it like so:

function meanVak(value) {
    return d3.mean(data, function(d) {return d [value] })
}

var meanProgramming = meanVak('programming');

But now i want a separate mean for 'programming' based on sex. So for female and male. How should i do that?

Upvotes: 1

Views: 2832

Answers (2)

Tomer
Tomer

Reputation: 17940

Seems to me like you need to create a new array that contains only Females/Males and then use the function with the new array, you can create the new array easily using jquery.map().

Look HERE for an example.

var data = [
 {"id":1,"sex":"Female","programming":5, "project":7}, 
 {"id":2,"sex":"Male","programming":8, "project":4}, 
 {"id":3,"sex":"Female","programming":5, "project":6}, 
 {"id":4,"sex":"Male","programming":4, "project":7} 
];

var newArray = $.map(obj,function(elem){
  return elem.sex === 'Female'? elem :null;
});

Upvotes: 0

Felan
Felan

Reputation: 1273

// I think the easiest way is to use the d3.nest function.  Perhaps something like ... 
var nest = d3.nest()
  .key(function(d) { return d.sex; })
  .sortKeys(d3.ascending)
  .rollup(function(d) {
    return {
      meanVakValue: d3.mean(d, function(g) { return g[value]; })
    };
  })
  .map(data);

// You may then need to turn it back into entries.  I had to use map first then extract to entries
// but I'm still getting my head around d3.
var nestedData = d3.entries(nest);

Upvotes: 1

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