Every example I have found shows all of the scatter plot points to be of random radii. Is it possible to have them all the same size? If I try to statically set the radius all of the circles will be very small (I'm assuming the default radius). However, if I use Math.random() as in most examples there are circles large and small. I want all the circles to be large. Is there a way to do that? Here's the code snippet forming the graph data using Math.random() (this works fine for some reason):
function scatterData(xData, yData)
{
var data = [];
for (var i = 0; i < seismoNames.length; i++)
{
data.push({
key: seismoNames[i],
values: []
});
var xVals=""+xData[i];
xVals=xVals.split(",");
var yVals=""+yData[i];
yVals=yVals.split(",");
for (var j = 0; j < xVals.length; j++)
{
data[i].values.push({
x: xVals[j],
y: yVals[j],
size: Math.random()
});
}
}
return data;
}
Math.random() spits out values between 0 and 1 such as 0.164259538891095 and 0.9842195005008699. I have tried putting these as static values in the 'size' attribute, but no matter what the circles are always really small. Is there something I'm missing?
Update: The NVD3 API has changed, and now uses pointSize, pointSizeDomain, etc. instead of just size. The rest of the logic for exploring the current API without complete documentation still applies.
For NVD3 charts, the idea is that all adjustments you make can be done by calling methods on the chart function itself (or its public components) before calling that function to draw the chart in a specific container element.
For example, in the example you linked too, the chart function was initialized like this:
var chart = nv.models.scatterChart()
.showDistX(true)
.showDistY(true)
.color(d3.scale.category10().range());
chart.xAxis.tickFormat(d3.format('.02f'));
chart.yAxis.tickFormat(d3.format('.02f'));
The .showDistX() and .showDistY() turn on the tick-mark distribution in the axes; .color() sets the series of colours you want to use for the different categories. The next too lines access the default axis objects within the chart and set the number format to be a two-digit decimal. You can play around with these options by clicking on the scatterplot option from the "Live Code" page.
Unfortunately, the makers of the NVD3 charts don't have a complete documentation available yet describing all the other options you can set for each chart. However, you can use the javascript itself to let you find out what methods are available.
Inspecting a NVD3.js chart object to determine options
Open up a web page that loads the d3 and nvd3 library. The live code page on their website works fine. Then open up your developer's console command line (this will depend on your browser, search your help pages if you don't know how yet). Now, create a new nvd3 scatter chart function in memory:
var testChart = nv.models.scatterChart();
On my (Chrome) console, the console will then print out the entire contents of the function you just created. It is interesting, but very long and difficult to interpret at a glance. And most of the code is encapsulated so you can't change it easily. You want to know which properties you can change. So run this code in the next line of your console:
for (keyname in testChart){console.log(keyname + " (" + typeof(testChart[keyname]) + ")");}
The console should now print out neatly the names of all the methods and objects that you can access from that chart function. Some of these will have their own methods and objects you can access; discover what they are by running the same routine, but replacing the testChart with testChart.propertyName, like this:
for (keyname in testChart.xAxis){console.log(keyname + " (" + typeof(testChart.xAxis[keyname]) + ")");}
Back to your problem. The little routine I suggested above doesn't sort the property names in any order, but skimming through the list you should see three options that relate to size (which was the data variable that the examples were using to set radius)
size (function)
sizeDomain (function)
sizeRange (function)
Domain and range are terms used by D3 scales, so that gives me a hint about what they do. Since you don't want to scale the dots, let's start by looking at just the size property. If you type the following in the console:
testChart.size
It should print back the code for that function. It's not terribly informative for what we're interested in, but it does show me that NVD3 follows D3's getter/setter format: if you call .property(value) you set the property to that value, but if you call .property() without any parameters, it will return back the current value of that property.
So to find out what the size property is by default, call the size() method with no parameters:
testChart.size()
It should print out function (d) { return d.size || 1}, which tells us that the default value is a function that looks for a size property in the data, and if it doesn't exist returns the constant 1. More generally, it tells us that the value set by the size method determines how the chart gets the size value from the data. The default should give a constant size if your data has no d.size property, but for good measure you should call chart.size(1); in your initialization code to tell the chart function not to bother trying to determine size from the data and just use a constant value.
Going back to the live code scatterplot can test that out. Edit the code to add in the size call, like this:
var chart = nv.models.scatterChart()
.showDistX(true)
.showDistY(true)
.color(d3.scale.category10().range())
.size(1);
chart.xAxis.tickFormat(d3.format('.02f'));
chart.yAxis.tickFormat(d3.format('.02f'));
Adding that extra call successfully sets all the dots to the same size -- but that size is definitely not 1 pixel, so clearly there is some scaling going on.
First guess for getting bigger dots would be to change chart.size(1) to chart.size(100). Nothing changes, however. The default scale is clearly calculating it's domain based on the data and then outputting to a standard range of sizes. This is why you couldn't get big circles by setting the size value of every data element to 0.99, even if that would create a big circle when some of the data was 0.01 and some was 0.99. Clearly, if you want to change the output size, you're going to have to set the .sizeRange() property on the chart, too.
Calling testChart.sizeRange() in the console to find out the default isn't very informative: the default value is null (nonexistent). So I just made a guess that, same as the D3 linear scale .range() function, the expected input is a two-element array consisting of the max and min values. Since we want a constant, the max and min will be the same. So in the live code I change:
.size(1);
to
.size(1).sizeRange([50,50]);
Now something's happening! But the dots are still pretty small: definitely not 50 pixels in radius, it looks closer to 50 square pixels in area. Having size computed based on the area makes sense when sizing from the data, but that means that to set a constant size you'll need to figure out the approximate area you want: values up to 200 look alright on the example, but the value you choose will depend on the size of your graph and how close your data points are to each other.
--ABR
P.S. I added the NVD3.js tag to your question; be sure to use it as your main tag in the future when asking questions about the NVD3 chart functions.
The radius is measured in pixels. If you set it to a value less than one, yes, you will have a very small circle. Most of the examples that use random numbers also use a scaling factor.
If you want all the circles to have a constant radius you don't need to set the value in the data, just set it when you add the radius attribute.
Not sure which tutorials you were looking at, but start here: https://github.com/mbostock/d3/wiki/Tutorials
The example "Three little circles" does a good step-by-step of the different things you can do with circles:
http://mbostock.github.io/d3/tutorial/circle.html
Related
My problem: i would like to find an automatic way to center labels in donut chart cells. In my case each cells contains an array of complex objects, what i want is to show the number of those objects.
See:
Playing with radius, allowed me to find those values:
First layer: -28
Second layer: -20
Third layer: -10
Fourth layer: -8
I applied it as a quick fix but i don't like this solution, as it's fixed for 4 layers (what if I need to add an other layer ? etc....) and using "magic numbers" is unmaintenable...
Do you have a better solution ?
You can test it here: https://jsfiddle.net/aliz/gwz7om9e/
Line 40:
pieSeries.labels.template.radius = am4core.percent(positionRadiusInPie);
Note:
Using those attributes didn't work: "horizontalCenter", "VerticalCenter", "textAlign", "align".
EDIT: response to Bhavik Kalariya
This is what I get if I force one radius for all layers.
You can at least get it down to just using one base constant of your choosing by using an adapter approach on the label's radius to calculate the value you want for each series that is added to the chart using whatever formula you choose. Here's a basic formula that gave good results for me with your setup, where BASE_INNER_LABEL_RADIUS is set to -45.
pieSeries.labels.template.adapter.add('radius', function(radius, target) {
var chart = target.baseSprite; //chart stored in baseSprite of the AxisCircularLabel
var index = chart.series.indexOf(target.dataItem.component); //corresponding series stored in the dataItem's component
return am4core.percent(BASE_INNER_LABEL_RADIUS / (index + 2)); //Uses singular constant defined elsewhere, which is used in all series
});
This will adjust itself according to the number of series you add to the chart. You can make this as robust as you want by making further tweaks if you have fewer series and want to make the labels even more centered.
Updated fiddle
Edit
If you want to be even more generic, you can get at the slice sprite directly through the target.dataItem.sprites array (typically the first element, though you can loop through and look for an object whose className is "Slice" if you want to be super safe about it) and calculate your desired radius value using any of the numeric properties it has, such as innerRadius.
pieSeries.labels.template.adapter.add('radius', function(radius, target) {
var chart = target.baseSprite; //chart stored in baseSprite of the AxisCircularLabel
var index = chart.series.indexOf(target.dataItem.component); //corresponding series stored in the dataItem's component
return -(target.dataItem.sprites[0].innerRadius) / (index + 3);
});
You'll want to adjust this accordingly, of course.
Fiddle
I'm using the d3 parcoords library. When I modify data plotted in a parallel coordinates chart, and reload the chart, the scale of the axis isn't refreshed.
I tried calling .autoscale(), but if I call it before .render(), it has no effect, and if I call it after .render(), then no polylines are drawn anymore.
$("#example").html(""); //to make sure "ghost" axes are removed
parcoords = d3.parcoords()("#example")
.data(parsedData)
.createAxes()
.brushMode("1D-axes")
.reorderable()//;
.detectDimensions()
.dimensions(dimensionObj)
.autoscale() //no visible effect if placed here
.render()
.updateAxes();
Not sure if this is related (although the issue started at the same time), I started specifying an order for the dimensions. To do this, instead of using an array containing the axes (dimensionArray), I use a JS object dimensionObj containing numbered "index" keys, as follows:
//dimensionArray = ["axis1", "axis2", "axis3", "axis4"]; //orderless array
//Default axes to display with predefined ordering
dimensionObj = {
"axis1": {index:0},
"axis2": {index:1},
"axis3": {index:2},
"axis4": {index:3}
}
For illustration purposes, the following screenshots show how on the top image, the scales are properly set, but on the second (updated) chart, some new polylines are going to 0 on the 1st and 3rd axis, but the scale isn't updated so lines go out of range.
Is there a simple way to refresh the axis scales when reloading a chart? Is it possible that using the JS object in .dimensions() is creating some conflicts with the underlying scale function?
Found what was causing this behaviour: an if statement in d3.parcoords.js pc.autoscale function which was only resetting scales if the yscale was not previously defined. Essentially I edited the if statement from original:
d3.keys(__.dimensions).forEach(function(k) {
if (!__.dimensions[k].yscale){
__.dimensions[k].yscale = defaultScales[__.dimensions[k].type](k);
}
});
to this (of course the if statement could be dropped altogether, I simply kept it in this form in case I need to revert to original version later for any reason):
d3.keys(__.dimensions).forEach(function(k) {
if (!__.dimensions[k].yscale || __.dimensions[k].yscale){
__.dimensions[k].yscale = defaultScales[__.dimensions[k].type](k);
}
});
I'm creating a plugin for my chart (in ChartJS 2.2.2), and for that I need the pixel position of each point of my dataset.
When inspecting the chart.config.data.datasets[0]._meta[0], I get back the following object:
But when I access the x field directly in my plugin code, the values returned are different. The commands:
chart.config.data.datasets[0]._meta[0].dataset._children[0]._model.x and
chart.config.data.datasets[0]._meta[0].data[0]._model.x (which yields the same value when looking it up in the chrome debugger) both return x = 3 instead of 44.67.
Why is this happening? What is the proper way to access the pixel coordinate of a point in my dataset?
The plugin is called multiple times, I was debugging only the initial values for the coordinates. Turns out the last calls were made with the correct value for X (44.67). I think this was happening because initially the canvas containing the chart was hidden (using ng-hide), only after init it was being shown.
It was rendered correctly though.
I'm working on a modification to vis.js's Graph3d to do a filled line graph, like this:
The hard part - unsurprisingly - is working out the rendering order for the polygons. I think I can do this by checking whether a ray from the viewer to a given line B crosses line A:
In this example, since line A is "in the way" of line B, we should draw line A first. I'll use a snippet of code from How do you detect where two line segments intersect? to check whether the lines cross.
However, I haven't figured how to find the position of the user's view. I kind of assumed this would be the camera object, so wrote a little bit of debug code to draw the camera on the graph:
var camera = this._convert3Dto2D(this.camera.getCameraLocation());
ctx.strokeStyle = Math.random()>0.5 ? 'ff0000' : '00ff00';
ctx.beginPath();
ctx.moveTo(camera.x, camera.y);
ctx.lineTo(camera.x, camera.y+5);
ctx.stroke();
In fact, the camera co-ordinates as measured by this are always at 0,0,0 on the graph (which would be the far top right on the above screengrab). What I need, I think, is effectively the bottom of the screen.
How can I find this? Or is there a better way to achieve what I'm trying to do?
I don't know if this is still an active issue, but FWIW, Graph3D has internal handling of the sort ordering.
All graph points are sorted with respect to the viewpoint, using a representative coordinate called point.bottom. The rendering is then done using this ordering, with the most distant elements drawn first. This works fine as long as none of the elements intersect; in that case, you can expect artefacts.
Basically, all you need to do, is define point.bottom per graph polygon, and Graph3D will then pick it up from there.
If you are still interested in working on this:
This happens in Graph3d.js, method Graph3d.prototype._calcTranslations(). For an example, have a look at how the Grid and Surface graph elements are initialized in Graph3d.prototype._getDataPoints(). The relevant code is:
obj = {};
obj.point = point3d;
obj.trans = undefined;
obj.screen = undefined;
obj.bottom = new Point3d(x, y, this.zRange.min);
My attempts to make my y values scale to logarithmic are turning my data upside-down.
I have vanilla js code and every implementation I read about are tied up in huge libraries of production code, I am not sure how/what to extract, I need some guidance as I could not put my finger on the problem weather it be sum or miss-use of the Math functions.
I am testing this by drawing the y 'data' to canvas (no libraries used) my x axis is constant 2px difference
Math.log uses e (2.718) as default base which is what I have read.. So I should be seeing my price data on a natural log scale but it wont work.
function logScale(data){
var log=data.slice(0);
var i=log.length;
while(i--){
log[i]=Math.log(data[i]); // should be natural but I don't see a change
// log[i]=Math.pow(Math.log(data[i]),10); //upside-down
// log[i]=Math.log(data[i])/Math.LN10; //no visible change when drawn to canvas
}
console.dir(log);
return log;
}
Another attempt from a couple of weeks ago where I am using the data min, max and difference. then removing all the infinity.
function á„logarithm(data){
var Lmax,Lmin,Ldif,Logarithm,infinity;
Lmax=Math.max.apply(this,data);
Lmin=Math.min.apply(this,data);
Ldif=(Lmax-Lmin);
Logarithm=[];
infinity=[];
for(var i=data.length-1;i>=0;i--){
Logarithm[i]=Math.log((data[i]-Lmin)/Ldif);
if(Logarithm[i]===-Infinity){infinity.push(i);}
}
for(var i=0;i<=infinity.length-1;i++){Logarithm.splice(infinity[i],1);}
return Logarithm;
}
The data looks different but still not quite like log scale. It is vertically warped to best describe it.
Please note jsfiddle-ing this won't work as The data is bitcoin prices (real time) so as there is no working code for a log scale there is no good way to show a comparison. Bitcoin or any other exchange data gets served as is so these functions would (if they worked) transfom any data array to log scale.
How do D3 do it? What is wrong with my code?