Develop Reference

Chart.js - consolidating days to month totals along the x (time) axis?

I'm feeding two daily statistics datasets into my chart. As you can see, each element represents the value for a particular day.
"data":[[{"y":"1", "x":"2018-04-01T04:00:00Z"},
{"y":"14", "x":"2018-04-02T04:00:00Z"},
{"y":"5", "x":"2018-04-03T04:00:00Z"},
{"y":"7", "x":"2018-04-04T04:00:00Z"},
...
The x axis is defined as follows:
xAxes: [{
type: 'time',
distribution: 'series',
time: {
unit: 'month'
}
}]
I (naively?) thought that the chart would be rolling up (summing) the day values into the appropriate month buckets but that's not what I got. Instead, I got monthly tick marks along the x-axis but data points are plotted within the chart at daily precision. (See screenshot.)
Before I go ahead and reprocess my dataset to manually roll up days into their respective month buckets, I'd like to hear whether the chart can in fact do this for me but I'm just setting this up wrong, or whether I do in fact need to take care of this summarization myself, before supplying the dataset to the chart for plotting.
Thanks for your advice!

I solved this by doing the rollup myself during the assembly of the underlying dataset which is then supplied to the chart.
var dayDate = new Date($scope.insights.locationMetrics[lm].metricValues[metric].dimensionalValues[dim].timeDimension.timeRange.startTime);
var monthDate = dayDate.getFullYear() + "-" + (dayDate.getMonth() + 1);
var hitCount = {
y: $scope.safeNumber($scope.insights.locationMetrics[lm].metricValues[metric].dimensionalValues[dim].value),
x: monthDate
}
var alreadyRecorded = hits[labelIdx].findIndex(obj => obj.x == hitCount.x)
if (alreadyRecorded > -1) {
hits[labelIdx][alreadyRecorded].y += Number(hitCount.y);
}
else {
hits[labelIdx].push(hitCount);
}
Extract the date from the underlying data source
Extract yyyy-mm from the date
Create the hitCount object
Check if the hitCount object is already in the array
If the object is already in the array then increment the hitCount (y) within the array.
Otherwise, push the object into the array.

Angular nvD3 Stacked Area Chart Data Series Format

I am trying to use my own data in a nvD3 stacked area chart. The sample data format from the Angular nvD3 site has a format like this:
[{
"key":"Series 1",
"values":[[1025409600000,0],[1028088000000,-6.3382185140371]]
},
{
"key":"Series 2",
"values":[[1025409600000,0],[1028088000000,0]]
}]
I have data coming from my database in this format:
[{
"Loc_Cnt":6,"Num_Cars":552,"Num_Employees":34,"active_month":"2017-10-01T00:00:00"
},
{
"Loc_Cnt":4,"Num_Cars":252,"Num_Employees":14,"active_month":"2017-11-01T00:00:00"
}]
I am trying to graph from my data, three series (Series 1: Flt_Cnt, Series 2: Num_Cars, Series 3: Num_Employees). For each series, the X axis value being the active_month date, and the Y axis value being the series value.
How can I either A) convert my data to look like the sample data easily, or B) use my data as is in the AngularJs nvd3 chart? I feel a .forEach on the array would not be efficient for larger data sets, and not as easy to read. I tried to use d3.nest in some way, but haven't been able to get a correct format. Thanks for your help!

It's not elegant, but I brute forced a way to my solution. If there are any better solutions, please do let me know.
var Loc_Cnt = [];
var Num_Cars = [];
var Num_Employees = [];
var obj = {};
//arr is the array of values in my format
arr.forEach(function (element) {
//need the date in milisecond format
var date = new Date(element.active_month);
var time = date.getTime();
//load corresponding arrays
Loc_Cnt.push([time, element.Loc_Cnt]);
Num_Cars.push([time, element.Num_Cars]);
Num_Employees.push([time, element.Num_Employees]);
});
//load each key/values pair into new object
obj["Loc_Cnt"] = Loc_Cnt;
obj["Num_Cars"] = Num_Cars;
obj["Num_Employees"] = Num_Employees;
//d3.entries creates an object of key/VALUEs
arrRollup = d3.entries(obj);
//change the key word values to value
var i;
for (i = 0; i < arrRollup.length; i++) {
arrRollup[i].values = arrRollup[i]['value'];
delete arrRollup[i].value;
}

Display labels on minor tick in Highcharts when using tickInterval

On a Highcharts chart with datetime axis, I am trying to highlight weeks. First, I had the idea to use the grid and to set tickInterval to 7*24*60*60*1000 and minorTickInterval to 24*60*60*1000. With the option gridLineWidth set to 2, the result is almost perfect.
The problem is when zooming: minor ticks appears but without label. I can not find how to add it. And the labels are not dynamic.
You can try this demo: https://jsfiddle.net/gdebrion/19x4nmp5/19/
First chart is the basic one. When you zoom you can see the changes in x-axis.
Second chart is mine. The weeks are visible but when zooming in until having a day display on the full width, and the only ticks visible are the minor one, without label…
Please tell me if you have an idea. Thanks!

The API does not provide a way to display labels on minor ticks.
http://www.highcharts.com/docs/chart-concepts/axes
MINOR TICKS
If the minorTickInterval option is set, minor ticks are laid out between the major ones. This includes minor tick marks, and minor grid lines, which have their own options for look and feel, but excludes labels.
Having a peek at the source code for Highcharts, I also do not see any label representation for minor ticks as there are for the major ticks (axis.labelEdge = [];) .
https://github.com/highcharts/highcharts/blob/b6bc666da00d37c5c4e3c0d7fe238b8526e583ea/js/parts/Axis.js
...
// Major ticks
axis.ticks = {};
axis.labelEdge = [];
// Minor ticks
axis.minorTicks = {};
// List of plotLines/Bands
...
UPDATE:
Here is a slightly rough solution to enable minor tick labels for highcharts:
http://jsfiddle.net/strince/deuez7gk/
The code doesn't handle overlapping labels when the zoom is far out so you'll need to zoom in a bit to see it work.
The chart code was updated with:
// Keep track of elements created.
var minorTickLabels = new Array();
...
events: {
load: function() { addMinorTickLabels(this); },
redraw: function() { addMinorTickLabels(this); }
}
...
function addMinorTickLabels(chart) {
// The elements need to be destroyed, otherwise a dictionary
// internal to highcharts will accumulate and pollute the chart.
for (var i = 0; i < minorTickLabels.length; i++) {
var textItem = minorTickLabels[i];
textItem.destroy();
}
minorTickLabels = new Array();
var axis0 = chart.xAxis[0];
var lastIndexFound = 0;
for (var tick in axis0.minorTicks) {
var el = axis0.minorTicks[tick];
// Skip double labels on major ticks.
var index = axis0.tickPositions.indexOf(el.pos, lastIndexFound);
if (index >= 0) {
listIndexFound = index;
continue;
}
var xPos = el.mark.getBBox().x;
var yPos = el.mark.getBBox().y;
var labelText = 0;
// The formatting parameters below should be passed in.
var textItem = chart.renderer.text(Highcharts.dateFormat("%d. %b", el.pos), xPos, yPos)
.css({
color: '#101010',
fontSize: '8px'
})
.attr({
rotation: -25,
zIndex: 6
});
// Add the tick label to the chart.
textItem.add();
minorTickLabels.push(textItem);
}
};

Chart.js Bar Chart - grouping and mapping data

I am trying to use Chart.js Bar Chart to display a set of data.
My data is weekly based so to my method I send the year and week and get the data back in 3 columns; Product, Area and Amount.
What I want is to have to Products horizontaly and in each Product I want different bars for each Area and offcourse the Amount verticaly. (Bonus: If an Area nothing in that product it should not be shown in that particular Product)
The problem is that the number of Products and the number of Areas can vary from each week. And I can't seem to find a good way to loop through the data and create the datasets the way chart.js wants.
Also tried using Underscore.js to group it but the fact that the each Area doesn't always have an amount for a spesific product seems to be causing some issues.
So I guess you have to loop through the data and map that data to another predefined array for each Area so it can match this structure somehow??
Also open for other Chart plugins, but really liked how Chart.js animates the data. And if I get this working I can probably figgure out an update method for when you change week.
To get the labels i can f.ex do this:
$.ajax({
....
success: function (d) {
var a = _.groupBy(d.data, function (d) { return d.Product });
var labels = [];
$.each(a, function (i, value) {
labels.push(i);
});
}
});

With data in this format
var myJSONData = [
{
Product: 'P1',
Area: 'A1',
Value: 12
},
...
]
You can use this function to convert it into the format Chart.js requires
var data = {
labels: [],
datasets: []
}
var colors = ['Red','Blue','Green', ...] // add as many colors as there will be areas (maximum)
myJSONData.forEach(function (e) {
// create labels
var labelIndex = data.labels.indexOf(e.Product)
if (labelIndex === -1) {
labelIndex = data.labels.length;
data.labels.push(e.Product);
// dummy entries for each dataset for the label
data.datasets.forEach(function (dataset) {
dataset.data.push(0)
})
}
// get the area dataset
var area = data.datasets.filter(function(area){
return (area.label === e.Area);
})[0]
// otherwise create it
if (area === undefined) {
area = {
label: e.Area,
// create a dummy array with an entry for each of the existing labels
data: data.labels.map(function () {
return 0;
}),
fillColor: colors[data.datasets.length]
};
data.datasets.push(area)
}
// set the value
area.data[labelIndex] = e.Value;
})
and use that to display the chart.
Fiddle - http://jsfiddle.net/jt4Lqkn3/
(Bonus: If an Area nothing in that product it should not be shown in
that particular Product)
You can't change any configuration to do this - there will be a space left for each series.
However you might want to set the strokeColor to a transparent value (e.g. strokeColor: "rgba(0, 0, 0, 0)", just below the fillColor line) and set the barStrokeWidth option to 0, so that 0 values don't show up at all on the chart (otherwise there will be thin line shown)
new Chart(ctx).Bar(data, {
barStrokeWidth: 0,
});

Efficiently detect missing dates in array and inject a null (highcharts and jquery)

I'm using highcharts.js to visualize data series from a database. There's lots of data series and they can potantially change from the database they are collected from with ajax. I can't guarantee that they are flawless and sometimes they will have blank gaps in the dates, which is a problem. Highcharts simply draws a line through the entire gap to the next available date, and that's bad in my case.
The series exists in different resolutions. Hours, Days and Weeks. Meaning that a couple of hours, days or weeks can be missing. A chart will only show 1 resolution at a time on draw, and redraw if the resolution is changed.
The 'acutal' question is how to get highcharts to not draw those gaps in an efficient way that works for hous, days and weeks
I know highcharts (line type) can have that behaviour where it doesn't draw a single line over a gap if the gap begins with a null.
What I tried to do is use the resolution (noted as 0, 1, 2 for hour day or week), to loop through the array that contains the values for and detect is "this date + 1 != (what this date + 1 should be)
The code where I need to work this out is here. Filled with psudo
for (var k in data.values) {
//help start, psudo code.
if(object-after-k != k + resolution){ //The date after "this date" is not as expected
data.values.push(null after k)
}
//help end
HC_datamap.push({ //this is what I use to fill the highchart later, so not important
x: Date.parse(k),
y: data.values[k]
});
}
the k objects in data.values look like this
2015-05-19T00:00:00
2015-05-20T00:00:00
2015-05-21T00:00:00
...and more dates
as strings. They can number in thousands, and I don't want the user to have to wait forever. So performance is an issue and I'm not an expert here either
Please ask away for clarifications.

I wrote this loop.
In my case my data is always keyed to a date (12am) and it moves either in intervals of 1 day, 1 week or 1 month. Its designed to work on an already prepared array of points ({x,y}). Thats what dataPoints is, these are mapped to finalDataPoints which also gets the nulls. finalDataPoints is what is ultimately used as the series data. This is using momentjs, forwardUnit is the interval (d, w, or M).
It assumes that the data points are already ordered from earliest x to foremost x.
dataPoints.forEach(function (point, index) {
var plotDate = moment(point.x);
finalDataPoints.push(point);
var nextPoint = dataPoints[index+1];
if (!nextPoint) {
return;
}
var nextDate = moment(nextPoint.x);
while (plotDate.add(1, forwardUnit).isBefore(nextDate)) {
finalDataPoints.push({x: plotDate.toDate(), y: null});
}
});

Personally, object with property names as dates may be a bit problematic, I think. Instead I would create an array of data. Then simple loop to fill gaps shouldn't be very slow. Example: http://jsfiddle.net/4mxtvotv/ (note: I'm changing format to array, as suggested).
var origData = {
"2015-05-19T00:00:00": 20,
"2015-05-20T00:00:00": 30,
"2015-05-21T00:00:00": 50,
"2015-06-21T00:00:00": 50,
"2015-06-22T00:00:00": 50
};
// let's change to array format
var data = (function () {
var d = [];
for (var k in origData) {
d.push([k, origData[k]]);
}
return d;
})();
var interval = 'Date'; //or Hour or Month or Year etc.
function fillData(data, interval) {
var d = [],
now = new Date(data[0][0]), // first x-point
len = data.length,
last = new Date(data[len - 1][0]), // last x-point
iterator = 0,
y;
while (now <= last) { // loop over all items
y = null;
if (now.getTime() == new Date(data[iterator][0]).getTime()) { //compare times
y = data[iterator][1]; // get y-value
iterator++; // jump to next date in the data
}
d.push([now.getTime(), y]); // set point
now["set" + interval](now.getDate() + 1); // jump to the next period
}
return d;
}
var chart = new Highcharts.StockChart({
chart: {
renderTo: 'container'
},
series: [{
data: fillData(data, interval)
}]
});
Second note: I'm using Date.setDay() or Date.setMonth(), of course if your data is UTC-based, then should be: now["setUTC" + interval].