Plotly.js - Plot histogram with frequency

Question

How to draw a histogram with frequency using Plotly.js?

Plotly.js provides API to draw histogram with set of values but not with frequency values.

You can find more about Plotly Histograms here - https://plot.ly/javascript/histograms/

Here is an example:

If the sample set is { 2, 3, 4, 5, 2, 2, 2, 3, 5 }. Plotly plots it this way - https://codepen.io/sgsvenkatesh/pen/eEyyMJ

var x = [2, 3, 4, 5, 2, 2, 2, 3, 5];

var trace = {
    x: x,
    type: 'histogram',
  };
var data = [trace];
Plotly.newPlot('myDiv', data);

But this is the data I have

x = [2, 3, 4, 5];
y = [4, 2, 1, 1];

This represents that values 0-2 are repeated 4 times, 2-3 is repeated 2 times and so on.

How can I plot this using Plotly.js?

Naren Murali Naren Murali · Accepted Answer · 2017-08-17T16:36:08

Check this mode of representation.

x = [2, 3, 4, 5];
y = [4, 2, 1, 1];

traces = [];
for (var i = 0; i <= x.length - 1; i++) {
    var yarray = new Array(y[i]).fill(y[i]);
    var trace = {};
    if (i === 0) {
        trace = {
            x: yarray,
            type: 'histogram',
            name: 0 + " to " + x[i]
        };
    } else if (i === x.length - 1) {
        trace = {
            x: yarray,
            type: 'histogram',
            name: x[i] + " and above"
        };
    } else {
        trace = {
            x: yarray,
            type: 'histogram',
            name: x[i - 1] + " to " + x[i]
        };
    }
    traces.push(trace);
}


var data = traces;
var layout = {barmode: "group"}; // there are three modes that can be set, "overlay", "stack", "group"
Plotly.newPlot('myDiv', data, layout);

 <script src="https://cdn.plot.ly/plotly-latest.min.js"></script>
 <div id="myDiv"></div>

Plotly.js - Plot histogram with frequency

1 Answers