strange issue with scales domain - d3.js

I'm having a really strange issue with scales, if I put the domain of the (in this case) yscale like this
.domain([0, d3.max(dataset, function (d) { return d.ycoord; })])
It sets up my axis wrong, like it is only show in half.
The strange thing is that, to solve this, I tried for a while and then put a / 1 at the end, like so:
.domain([0, d3.max(dataset, function (d) { return (d.ycoord / 1); })])
And it did show the axis correctly, as in these screenshots
And also here there's the full code on jsfiddle:
jsfiddle link
So my question is: why it behaves like this? I'm really clueless about this and was wondering if anyone was able to solve this!

The problem is that what you're interpreting as numbers (ycoord) are actually strings because they come directly from the CSV. That is, instead of 140 you have "140", which as a string is indeed smaller than "95". So the determined maximum for the scale is incorrect. The D3 functions that actually require numbers (such as the scale function) implicitly convert the strings you give them to numbers, so there's no error message.
To fix this, simply convert your strings to numbers before you do anything else.
dataset.forEach(function(d) { d.ycoord = +d.ycoord; });

Related

How to generate line chart with discrete value, not time serial, as x-axis

Sorry for this silly question, but I am lost and hope any other expert can help me.
I need to draw a bar chart, but the x axis is NOT time series, it is discrete values.
var ndx = crossfilter( self.getStatus( contracts ));
var skuDim = ndx.dimension( function(d){
return d.sku;
});
var skuDimCount = skuDim.group().reduceCount();
var chartLineContractSku= dc.barChart("#chart-line-contract-sku");
chartLineContractSku
.width(500)
.height(200)
.dimension(skuDim)
.group(skuDimCount)
.x(d3.scale.linear().domain(skus))
.legend(dc.legend());
the skus is:
array of sku:
["PAR-ND-SRX1-SPCNPC", "SVC-ND-M10i", "SVC-CP-SRX3400", "SVC-ND-SRX3400", "SVC-ND-SRX3-IOC", "SVC-CP-SRX3-IOC", "SVC-CP-SRX3-NPC", "SVC-3-ND-SRX3-IOC", "SVC-CP-SRX3-SPC", "SVC-ND-SRX3-SPC"]
which is used to group dimension the input data.
But the output graph is always empty.
Can anyone tell me how to fix this? And how to generate the barChart with discrete value? Also, another question is how to make the label vertical? as we have quite a lot skus.
Thanks
Gordon is correct in saying that you should use ordinal scale to get your desired result. Replace your d3.scale.linear code with
x(d3.scale.ordinal().domain(skus))
Look at this as an example
http://bost.ocks.org/mike/bar/3/

Ordering chords based on some property of the source data

I have a chord diagram in d3 that looks something like this:
The color of each group is calculated base on a property of the source data (before being transformed to a matrix) and is looked up from the index of each group with something like this:
var groupPath = group.append("path")
.attr("id", function(d, i) { return "group" + i; })
.attr("d", arc)
.style("fill", function(d, i) { return MySourceData[i].inArea ? "blue" : "red"; });
Now what I'd like to do is sort the chords so that all the blues are together and all the reds are together, but there doesn't seem to be a simple way to do that. I know you provide a function to sortGroups (and sortSubGroups for that matter), but it seems the arguments passed to the function are only the values of the chords and I would need to have the indexes to be able to figure out if they should be grouped together or not.
Is there any simple way to sort the groups based on some criteria that is ultimately derived from the index?
It seems the best way to achieve this is to simply order my source data first before I transform it into a matrix. This works fine if the data isn't going to change (which, in my case it wasn't), but if you had data that might change and in changing might end up needing to be resorted, this would be a real pain since you'd need to reorder the matrix.

NVD3.js multiChart x-axis labels is aligned to lines, but not bars

I am using NVD3.js multiChart to show multiple lines and bars in the chart. All is working fine, but the x-axis labels is aligned only to the line points, not bars. I want to correctly align labels directly below the bars as it should. But I get this:
With red lines I marked where the labels should be.
I made jsFiddle: http://jsfiddle.net/n2hfN/
Thanks!
As #Miichi mentioned, this is a bug in nvd3...
I'm surprised that they have a TODO to "figure out why the value appears to be shifted" because it's pretty obvious... The bars use an ordinal scale with .rangeBands() and the line uses a linear scale, and the two scales are never made to relate to one another, except in that they share the same endpoints.
One solution would be to take the ordinal scale from the bars, and simply adjust it by half of the bar width to make the line's x-scale. That would put the line points in the center of the bars. I imagine that something similar is done in the nv.models.linePlusBarChart that #LarsKotthoff mentioned.
Basically, your line's x-scale would look something like this:
var xScaleLine = function(d) {
var offset = xScaleBars.rangeBand() / 2;
return xScaleBars(d) + offset;
};
...where xScaleBars is the x-scale used for the bar portion of the chart.
By combing through the source code for nvd3, it seems that this scale is accessible as chart.bars1.scale().
Maybe someday the authors of nvd3 will decide that their kludge of a library deserves some documentation. For now, I can show you the kind of thing that would solve the problem, by making a custom chart, and showing how the two scales would relate.
First, I'll use your data, but separate the line and bar data into two arrays:
var barData = [
{"x":0,"y":6500},
{"x":1,"y":8600},
{"x":2,"y":17200},
{"x":3,"y":15597},
{"x":4,"y":8600},
{"x":5,"y":814}
];
var lineData = [
{"x":0,"y":2},
{"x":1,"y":2},
{"x":2,"y":4},
{"x":3,"y":6},
{"x":4,"y":2},
{"x":5,"y":5}
];
Then set up the scales for the bars. For the x-scale, I'll use an ordinal scale and rangeRoundBands with the default group spacing for nvd3's multiBar which is 0.1. For the y-scale I'll use a regular linear scale, using .nice() so that the scale doesn't end on an awkward value as it does by default in nvd3. Having some space above the largest value gives you some context, which is "nice" to have when trying to interpret a chart.
var xScaleBars = d3.scale.ordinal()
.domain(d3.range(barData.length))
.rangeRoundBands([0, w], 0.1);
var yScaleBars = d3.scale.linear()
.domain([0, d3.max(barData, function(d) {return d.y;})])
.range([h, 0])
.nice(10);
Now here's the important part. For the line's x-scale, don't make a separate scale, but just make it a function of the bars' x-scale:
var xScaleLine = function(d) {
var offset = xScaleBars.rangeBand() / 2;
return xScaleBars(d) + offset;
};
Here's the complete example as a JSBin. I've tried to document the major sections with comments so it's easy to follow the overall logic of it. If you can figure out from the nvd3 source code exactly what each of the elements of the multiChart are called and how to set the individual scales of the constituent parts, then you might be able to just plug in the new scale.
My feeling on it is that you need to have a pretty good handle on how d3 works to do anything useful with nvd3, and if you want to customize it, you're probably better off just rolling your own chart. That way you have complete knowledge and control of what the element classes and variable names of the parts of your chart are, and can do whatever you want with them. If nvd3 ever gets proper documentation, maybe this will become a simple fix. Good luck, and I hope this at least helps you get started.

Trying to modify Voronoi Map in D3JS

I am trying to modify this D3 example to use with my dataset
http://mbostock.github.io/d3/talk/20111116/airports.html
I think my problem is creating the array of coordinates for calculating the Voronoi polygons, but at this point I'm not sure.
I'm getting a Uncaught TypeError: Cannot read property '0' of undefined error that points to the line where I am calling the array. The code is live, please see here
http://cds.library.brown.edu/projects/mapping-genres/symbol-maps/brown-voronoi-map.html
The map displays just fine, but the data points, the radio button, and the voronoi lines do not appear (I'm not trying to show lines between data points, so that code has been removed).
Any thoughts or suggestions would be most appreciated. Many thanks!
There are a number of small things going on here which can be easily sorted out but some will require a bit of work. The first is that you're using a new version of d3 (v3) and the example you're trying to replicate is an older version. There have been significant changes between the versions on the mapping side of things. So you can either use an old version of d3 (v2 will work I think) or investigate the changes.
The Uncaught TypeError: Cannot read property '0' of undefined error is being generated because d3.geom.voronoi(positions) line is producing NaN. I'm not 100% sure why but you could just filter these out to get a temporary fix. A simple filter would be something like:
g.append("svg:path")
.attr("class", "cell")
.attr("d", function(d, i) {
if (polygons[i][0][0]) {
return "M" + polygons[i].join("L") + "Z";
}
})
with the if true when there is not a false value (NULL, NaN, etc) in the first element of the polygon. Please note that this is temporary fix while you investigate why you're getting NaN and this will not produce the correct voronoi polygons.
The fix for the data points is very simple, you just have to set the radius to something greater than 0 such as 10 (although I imagine that you might want to scale the dots to a property of your data like TotalPublished). For instance see the last line:
circles.selectAll("circle")
.data(locations.rows
.sort(function(a, b) { return b.TotalPublished - a.TotalPublished; }))
.enter().append("svg:circle")
.attr("transform", function(d) { return "translate(" + projection(d.coordinates) + ")"; })
.attr("r", 10);
The radio button (or checkbox) does not show up as it's not generated by the javascript (although it can be). In the example you refer to its generated in the html in this snippet:
<div style="position:absolute;bottom:0;font-size:18px;">
<input type="checkbox" id="voronoi"> <label for="voronoi">show Voronoi</label>
</div>
Once you've worked through this you'll need to get the voronoi lines working. I think with your code as is the voronoi lines won't show up as the checkbox is not checked. So you could comment these lines out and see what happens. A quick tip with paths is that if you want to just show the lines you need to set the fill style to none and the stroke to whatever colour you want. If you don't set the fill to none you'll just get a black screen.

Display x axis properly on stacked bar chart

Hey so I'm having difficulty with the positioning of my stacked bar chart. It's showing up, I'm just having difficulty declaring it's x axis. Here is the jsfiddle: http://jsfiddle.net/E2HST/
var xTimeScale = d3.time.scale().
domain([new Date(data[0].date), d3.time.day.offset(new Date(data[data.length - 1].date), 1)])
.range([0, width]);
is obviously part of the problem, I pulled code and have unfortunately fallen into the trap of not fully understanding it.
var bars = svg.selectAll(".bar")
.data(data).enter()
.append("g")
.attr("class","bar")
.attr("transform", function(d){
return "translate("+xTimeScale(d.date)+",0)"
})
I've tried swapping in d.year for d.date seeing as there is no more d.date but it's throwing up errors. Any help would be greatly appreciated.
The simple answer is that the objects in your data array do not have a date key, so your xTimeScale domain is undefined. An easy way to correct this would be to create this key for each data item:
data.forEach( function(d) { d.date = new Date(d.year, 0, 1); });
Which creates the date as January 1st of the year variable. This basically solves your x-axis problem.
I would, however, suggest that your data would be better suited to using an ordinal scale, since you only have yearly data.
A couple of other small things:
Your x-axis definition has way too many ticks, consider changing this
Consider adding css styles for .axis elements, to improve readability
An updated fiddle with these slight changes is at http://jsfiddle.net/E2HST/1/

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