Is there a way to filter data in Chart.js?

Question

I'm working with Chart.js and I'm wondering if there's a way when you click on part of a pie chart, it filters the bar chart.

Answer 1

Since this is a Chart.js question :-), this is how you do it Chart.js (and it's not too complex either)

Setting up the Pie Chart

// pie
var data = [
    {
        value: 300,
        color: "#F7464A",
        highlight: "#FF5A5E",
        label: "Red",
        subData: [28, 48, 40, 19, 86, 27, 190]
    }, {
        value: 50,
        color: "#46BFBD",
        highlight: "#5AD3D1",
        label: "Green",
        subData: [90, 28, 48, 40, 19, 86, 127]
    }, {
        value: 100,
        color: "#FDB45C",
        highlight: "#FFC870",
        label: "Yellow",
        subData: [28, 48, 40, 19, 86, 27, 190]
    }
]

var canvas = document.getElementById("chart");
var ctx = canvas.getContext("2d");
var myPieChart = new Chart(ctx).Pie(data);

Setting up the Bar Chart using Pie Data

// bar using pie's sub data
var bardata = {
    labels: ["Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun"],
    datasets: [
        {
            label: "My Second dataset",
            fillColor: "rgba(151,187,205,0.5)",
            strokeColor: "rgba(151,187,205,0.8)",
            highlightFill: "rgba(151,187,205,0.75)",
            highlightStroke: "rgba(151,187,205,1)",
            data: data[0].subData.map(function (point, i) {
                var pointTotal = 0;
                data.forEach(function (point) {
                    pointTotal += point.subData[i]
                })
                return pointTotal;
            })
        }
    ]
};

var subcanvas = document.getElementById("subchart")
var subctx = subcanvas.getContext("2d");
var myBarChart = new Chart(subctx).Bar(bardata);

Updating Bar data when Clicking Pie

// connect them both
canvas.onclick = function (evt) {
    var activeSector = myPieChart.getSegmentsAtEvent(evt);

    myBarChart.datasets[0].bars.forEach(function (bar, i) {
        var pointTotal = 0;
        data.forEach(function (point, j) {
            if (activeSector.length === 0 || point.label === activeSector[0].label)
                pointTotal += data[j].subData[i]
        })

        bar.value = pointTotal;
    });

    myBarChart.update();
};

Clicking outside the pie (but in the pie chart's canvas) resets the bar chart.

---

Fiddle - http://jsfiddle.net/0zwkjv8a/

Answer 2

Other answers posted already cover what I would generally advise here which is to use dc-js if you want crossfilter enabled charts out of the gate. I would have commented on this answer, but I don't have enough reputation so I'm posting this as option 'c.)' where 'a.)' is using dc-js and 'b.)' is making some modifications to an existing Chart.js chart.

Option 'c.)' is to extend the Chart.js chart type and make the child chart work like a dc-js chart. Chart.js chart types follow an inheritance hierarchy, so if you like a chart that already exists you can wrap its prototype methods with some of your own. Additionally important to this option, in the selected answer to the stack overflow question with heading 'dc.js - Listening for chart group render', it is described how the current implementation of dc-js's chartRegistry object is fairly decoupled from d3 or dc internals, so any chart implementing chartRegistry's interface can be part of a chartGroup.

I was in the position of wanting very much to use Polar Area Charts in a dataset where I was already using a chart group full of dc-js charts to crossfilter the data. I wrote an extension for Polar Area charts that could serve as an example of one way (I'm going to go ahead and say probably not the best way) to extend a chart type with dc-js like behaviors. The repo for this is at https://github.com/nsubordin81/Chart.dc.js, Licensed under an MIT License, and in case that ever goes anywhere, all of the code is copied into the example fiddle: http://jsfiddle.net/nsubordin81/3w725o3c/1/

Chart.dc.js v. 0.1.0

MIT Licensed: opensource.org/licenses/MIT Copyright (c) 2015 Taylor Bird

      (function () {
    "use strict";

    var root = this,
        Chart = root.Chart,
        dc = root.dc,
        helpers = Chart.helpers,
        //class for data structure that manages filters as they relate to chart segments. This should probably be generalized to chart elements of all kinds.
        FilterManager = function (segmentList) {

            //private member variable
            var filterMap = [];

            //constructor
            //accepts a list of SegmentArcs that have had the extra properties added to them
            for (var i = 0; i < segmentList.length; i++) {
                add(segmentList[i].segmentID);
            }

            //private methods
            function testOnAll(test) {
                var testResult = true;
                for (var i = 0; i < filterMap.length; i++) {
                    //one failure of test means testOnAll fails
                    if (!test(filterMap[i])) {
                        testResult = false;
                    }
                }
                return testResult;
            }
            //add a filter, pretty much just a wrapper for push
            function add(segmentID) {
                filterMap.push({
                    "segmentID": segmentID,
                        "active": false
                });
            }
            //remove a filter by id, returns removed filter
            function remove(segmentID) {
                var removed = filterMap.find(segmentID);
                filterMap = filterMap.filter(function (elem) {
                    return elem.segmentID !== segmentID;
                });
                return removed;
            }
            //return this segment if it is filtered
            function find(segmentID) {
                for (var i = 0; i < filterMap.length; i++) {
                    if (filterMap[i].segmentID === segmentID) {
                        return filterMap[i];
                    }
                }
                return -1;
            }

            //public methods
            return {
                //tell me if the filter for this segment is active
                isActive: function (segmentID) {
                    var filter = find(segmentID);
                    if (filter === -1) {
                        console.error("something went wrong, the filter for this segment does not exist");
                    }
                    return filter.active;
                },
                //for the given segment, activate or deactivate its filter. return whether the filter is on or off.
                flip: function (segmentID) {
                    var filter = find(segmentID);
                    if (filter === -1) {
                        console.error("something went wrong, the filter for this segment does not exist");
                    }
                    filter.active ? filter.active = false : filter.active = true;
                    return filter.active;
                },
                //if all filters are on, we want to be able to quickly deactivate them all
                turnAllOff: function () {
                    for (var i = 0; i < filterMap.length; i++) {
                        filterMap[i].active = false;
                    }
                },
                //tell me if all of the filters are off
                allOff: function () {
                    return testOnAll(function (elem) {
                        return !elem.active;
                    });
                },
                //tell me if all the filters are on
                allOn: function () {
                    return testOnAll(function (elem) {
                        return elem.active;
                    });
                }
            }
        };

    //utility function, Takes an array that has some property as its key
    //and forms a javascript object with the keys as properties so we can get O(1) access
    function createKeyMap(arr, propName) {
        var keyMap = {}
        for (var i = 0; i < arr.length; i++) {
            keyMap[arr[i][propName]] = arr[i];
        }
        return keyMap;
    }


    Chart.types.PolarArea.extend({
        name: "PolarAreaXF",
        //this will have to be a member
        dimension: undefined,
        colorTypes: {
            "NORMAL": 0,
                "HIGHLIGHT": 1,
                "FILTER": 2,
                "FILTER_HIGHLIGHT": 3
        },
        chartGroup: undefined,
        filters: undefined,
        originalDataKeys: undefined,
        initialize: function (data) {
            //--PRE--
            var that = this;
            //Polar Area initialize method is expecting (data, options) in arguments,
            //but we pass in an array of components to merge. Let's clean this up.
            var argsArray = Array.prototype.slice.call(arguments);
            //remove the first element of arguments which is our array, then we do a bunch of Chartjs converison on it . . . 
            argsArray.splice(0, 1);
            //TODO - check if data is an array, if not, put a message in a console explaining how you are supposed to send data in an array 
            this.dimension = data.dimension;
            data.chartGroup ? this.chartGroup = data.chartGroup : this.chartGroup = 0;
            //short but magical line. Now we are linked with all dc charts in this group!
            dc.registerChart(this, this.chartGroup);
            var data = this.setupChartData(data.colors, data.highlights, data.labels);
            //... and push the result in its place.
            argsArray.unshift(data);
            //originalDataArray -- this is used as a reference to the original state of the chart, since segments can come and go,
            //we use this to track what a segment's original colors were when adding it back in. This would mess up adding a truly new segment, but who 
            //is gonna do that? Assumption here is dimensions start with so many groups and that is it.
            this.originalDataKeys = createKeyMap(data, "key");
            //parent's initialize
            Chart.types.PolarArea.prototype.initialize.apply(this, argsArray);
            //--modify SegmentArcs--
            //assign colors and ids to all existing segment arcs
            var mySegments = this.segments;
            for (var i = 0; i < mySegments.length; i++) {
                mySegments[i].colorList = [undefined, undefined, "#777", "#aaa"];
                mySegments[i].colorList[this.colorTypes.NORMAL] = mySegments[i].fillColor;
                mySegments[i].colorList[this.colorTypes.HIGHLIGHT] = mySegments[i].highlight;
                mySegments[i].segmentID = i;
                mySegments[i].key = data[i].key;
            }
            //add methods to SegmentArc objects that will color them one way or the other depending on their filter
            this.SegmentArc.prototype.setIncluded = function (include) {
                if (include) {
                    this.fillColor = this.colorList[that.colorTypes.NORMAL];
                    this.highlight = this.colorList[that.colorTypes.HIGHLIGHT];
                } else {
                    this.fillColor = this.colorList[that.colorTypes.FILTER];
                    this.highlight = this.colorList[that.colorTypes.FILTER_HIGHLIGHT];
                }
            }
            //--initialize filters--
            this.filters = new FilterManager(this.segments);
            //handle clicks on segments as filter events, do the styling and crossfilter changes at the Chart level in the filter method.
            helpers.bindEvents(this, ["mousedown"], function (evt) {
                var activeSegment = Chart.types.PolarArea.prototype.getSegmentsAtEvent.apply(this, [evt])[0];
                this.handleFilter(activeSegment);
            });

        },
        //convert crossfilter dimension into chart.js Polar Area data object array
        setupChartData: function (colors, highlights, labels) {
            var chartJSible = [];
            //probably need checks here to make sure client actually passed in a crossfilter dimension
            var grouped = this.dimension.group().reduceCount().top(Infinity);
            //probably need checks here to either fail if the arrays aren't all long enough or have some way to add random colors/highlights if they are shorter.
            for (var i = 0; i < grouped.length; i++) {
                var dataObject = {
                    value: grouped[i].value,
                    key: grouped[i].key,
                    color: colors[i],
                    highlight: highlights[i],
                    label: labels ? (labels[i] ? labels[i] : grouped[i].key) : grouped[i].key
                };
                chartJSible.push(dataObject);
            }

            return chartJSible;

        },
        //figure out what changed between Chart.js' internally maintained data object array and crossfilter's dimension data. use the saved information
        //about what colors and highlight a key has to rebuild the segmentArc list 'segments'. can't trash the old, it might mess up the animations. 
        redraw: function () {
            var grouped = this.dimension.group().reduceCount().top(Infinity);
            var currentSegmentKeys = createKeyMap(this.segments, "key");
            var crossfilterGroupKeys = createKeyMap(grouped, "key");
            //loop through the segment list, if the segment for a group is already there, update the value, if it is not there, add it back using the 
            //original data as a guide for what it's color and highlight color should be. if there are segments in the existing list

            var length = Math.max(this.segments.length, grouped.length);
            //going through both lists, whichever is longer
            for (var i = 0; i < length; i++) {
                var sList = this.segments;
                var gList = grouped;
                //only do this part if we still have items in the new filtered list
                if (gList[i]) {
                    //we already have a segment for this crossfilter group, just get that segment and update its value 
                    if (currentSegmentKeys[gList[i].key]) {
                        currentSegmentKeys[gList[i].key].value = gList[i].value;
                    } else {
                        //the chart doesn't have the crossfilter group item, add a new segment with the right colors and values from original data
                        var theSegment = this.originalDataKeys[gList[i].key];
                        this.addData(theSegment, 0, true);
                    }
                }
                //only do this part if we still have items in the current chart segment list
                if (sList[i]) {
                    //we don't have this segment in the new crossfilter group, remove it from the chart 
                    if (!crossfilterGroupKeys[sList[i].key]) {
                        this.removeData(i);
                    }
                }
            }

            this.update();
        },
        filterAll: function () {
            this.dimension.filterAll();
            this.filters.turnAllOff();
            this.colorMeIn();
            this.redraw();
        },
        handleFilter: function (clicked) {
            //after we have all of the filters figured out, change the colors to reflect what they should be and update the chart
            this.filters.flip(clicked.segmentID);
            this.colorMeIn();
            if (this.filters.allOn()) {
                this.dimension = this.dimension.filterAll();
                dc.redrawAll(this.chartGroup);
                this.filters.turnAllOff();
            }
            dc.redrawAll(this.chartGroup);
        },
        colorMeIn() {
            var activeFilters = [];
            var segments = this.segments;
            for (var i = 0; i < segments.length; i++) {
                var segment = segments[i];
                if (this.filters.isActive(segment.segmentID) || this.filters.allOff()) {
                    segment.setIncluded(true);
                    activeFilters.push(segment.key);
                } else {
                    segment.setIncluded(false);
                }
            }
            this.dimension = this.dimension.filterFunction(function (d) {
                for (var i = 0; i < activeFilters.length; i++) {
                    if (d === activeFilters[i]) {
                        return true;
                    }
                }
                return false;
            });
        }
    })
}).call(this);