What is String or where does this come from? - javascript

While trying to understand d3 I saw the line .text(String);. I could not understand what String is suppose to be. I thought maybe its an empty string (nope), a method (i didnt see that in the api reference) and pondered what else it could be.
I commented it out below and got expected results. What I don't understand is what is String and why does it work. With this line my 3 squared boxes has text (its a internal value of the data it will represent later) while commented out it does not.
Demo
Html
<div class='chart' id='chart-10'/>
<script src="http://d3js.org/d3.v3.min.js"></script>
JS:
var w = 360;
var h = 180;
var svg = d3.select("#chart-10").append("svg")
.attr("width", w)
.attr("height", h);
var g = svg.selectAll(".data")
.data([50,150,250])
.enter().append("g")
.attr("class", "data")
.attr("transform", function(d, i) { return "translate(" + 20 * (i + 1) + ",20)"; });
g.append("circle")
.attr("class", "little")
.attr("r", 1e-6);
g.append("rect")
.attr("x", -10)
.attr("y", -10)
.attr("width", 20)
.attr("height", 20)
.style("fill", "lightgreen")
.style("stroke", "green");
g.append("text")
.attr("dy", ".35em")
.attr("text-anchor", "middle")
;// .text(String);
g.attr("transform", function(d, i) { return "translate(" + 20 * (i + 1) + ",20)"; });
g.select("rect").style("opacity", 1);
g.select("circle").attr("r", 1e-6);
var t = g.transition().duration(750);
t.attr("transform", function(d, i) { return "translate(" + d + ",90)"; });
t.select("circle").attr("r", Math.sqrt);
t.select("rect").style("opacity", 1e-6);

It looks like the String constructor. According to d3 documentation, as pointed out by Matt:
if value is a function, then the function is evaluated for each selected element (in order), being passed the current datum d and the current index i, with the this context as the current DOM element. The function's return value is then used to set each element's text content.
So, you set g.data to [50,150,250] a few lines before. Each number is converted to a String object by the String constructor, returned and used as the text values of your DOM nodes.

Related

d3.js add second label to bar chart

2 part question:
I have a bar chart with created using multiple arrays. These arrays contain the % wins of baseball teams; the relevant team colours; and their names.
I can create one set of labels on the chart, either the names or the win %. However I can't get both on at the same time. See below.
The code I am using is:
let WinsLabel = svgContainer.selectAll("text")
.data(d3.zip(TeamArray, WinPercArray, Colours));
WinsLabel.enter()
.append("text")
.attr("fill", "black")
.attr("x", function(d, i) {
return 45 + (i * 50);
})
.attr("y", 700)
.transition()
.duration(1000)
.attr("x", function(d,i){
return 70 + (i*50);
})
.attr("y", function(d){
return 685 - d[1];
})
.attr("text-anchor","middle")
.attr("font-family", "sans-serif")
.attr("font-size", "15px")
.attr("fill", "black")
.text(function(d){
return d[1]/10 + "%";
});
let TeamLabel = svgContainer.selectAll("text")
.data(d3.zip(TeamArray, WinPercArray, Colours));
TeamLabel.enter()
.append("text")
.attr("fill", "black")
.attr("x", function(d, i) {
return 45 + (i * 50);
})
.attr("y", 700)
.transition()
.duration(1000)
.attr("x", function(d,i){
return 70 + (i*50);
})
.attr("y", function(d){
return 700 - d[1]/2;
})
.attr("text-anchor","middle")
.attr("font-family", "sans-serif")
.attr("font-size", "15px")
.attr("fill", "white")
.text(function(d){
return d[0];
});
When I run the code with both scripts, only the win % shows up, but the names don't. In order to get the names to show up I have to remove the first label.
The 2 parts to my question are:
How would I get both sets of labels to show up at the same time?
How can I get the names to be arranged vertically in the rectangles/bars?
D3 stands for data driven something; and it's core principle is based on linking elements / selection, with data. When you set data, (var selection = selectAll(...).data(...)), you get 3 cases to think about:
Some existing elements can be linked to certain item in new data. You access them using selection
Some elements cannot be linked to any item in new data. You access them using selection.exit()
Some items in new data cannot be linked to any element from selection. You access them by using selection.enter()
In its simplest case, the linking between data and elements is made by index -- ie first element in selection is linked with first item in data array, second with second, and so on. The d3 cannot find element for the data item (= gets put into .enter() selection) if and only if (in this by-index context) the index of that data item is bigger than the size of the selection.
On your initial select
let WinsLabel = svgContainer.selectAll("text")
.data(d3.zip(TeamArray, WinPercArray, Colours));
The selection is empty, since there are no text tags yet. And since its empty, all of the to-be-created placeholders are inside .enter() selection. However, on your next select for the other label type
let TeamLabel = svgContainer.selectAll("text")
.data(d3.zip(TeamArray, WinPercArray, Colours));
The selection is of the size of the passed data, and thus .enter() selection is empty; it's the TeamLabel selection that contains all of the old elements (percentage label text tags), but they got their data values reassigned.
Andrew proposed one solution to assign classes, but personally I'd take all elements that relate to same team and put it under one group.
var TeamArray = ["Yankees", "Rays", "RedSox", "Jays","Orioles", "Twin", "Indians", "WhiteSox", "Detroit", "Royals", "Astros", "Rangers", "A's", "Angels","Mariners"];
var WinPercArray = [653, 609, 540, 400, 300, 667, 521, 458, 383, 347, 660, 511, 500, 458, 442];
var Colours = ["#003087", "#092C5C", "#BD3039", "#134A8E", "#DF4601", "#002B5C", "#0C2340", "#C4CED4", "#FA4616", "#BD9B60", "#EB6E1F", "#C0111F", "#003831", "#003263", "#005C5C"];
var data = d3.zip(TeamArray, WinPercArray, Colours);
var svg = d3.select('body').append('svg').attr('height', 300).attr('width', 800);
var teams = svg.selectAll('g.teams')
.data(data);
var scale = d3.scaleLinear()
.domain([0, 1000])
.range([200, 0]);
var teamsEnter = teams.enter()
.append('g')
.classed('team', true)
.attr('transform', function(d, i){
return 'translate(' + (i*50) + ',0)';
})
teamsEnter.append('rect')
.attr('width', 50)
.attr('y', function(d) { return scale(d[1]); })
.attr('height', function(d) { return scale(0) - scale(d[1]); })
.style('fill', function(d) { return d[2]; });
teamsEnter.append('text')
.attr('x', 25)
.attr('y', function(d) { return scale(d[1]) - 30; })
.text(function(d){ return d[0]; });
teamsEnter.append('text')
.attr('x', 25)
.attr('y', function(d) { return scale(d[1]) - 15; })
.text(function(d){ return d[1]; });
text {
text-anchor: middle;
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/5.7.0/d3.min.js"></script>
Groups in some way act as encapsulation of inner items, so you can mentally separate data binding to groups (ie when to create / update / delete it), from actual logic that takes place when working with its children

Circular Picture on D3JS

I'm trying to create a rounded picture using D3JS in a graph.
Here is my fiddle: http://jsfiddle.net/vsvuyusg/1/
As you can see, on line 99 we have this code (that supposed to work):
var defs = svg.append('svg:defs');
node.each(function(d) {
var _node = d3.select(this);
defs.append("svg:pattern")
.attr("id", "circlePicture_" + d.name)
.append("svg:image")
.attr("xlink:href", function(d) {
var rnd = Math.floor(Math.random() * 64 + 1);
var imagePath =
"http://www.bigbiz.com/bigbiz/icons/ultimate/Comic/Comic"
+ rnd.toString() + ".gif";
console.log(imagePath);
return imagePath;
})
.attr("width", 12)
.attr("height", 12)
.attr("x", 0)
.attr("y", 0);
_node.append("circle")
.attr("cx", 12)
.attr("cy", 12)
.attr("r", 12)
.style("fill", "url(#circlePicture_" + d.name + ")")
});
I create a pattern for each image, setting the node name on it and use it to fill a circle appended to the node (using the same node name as ref).
I've noticed that after the code executes, I cannot find any def or pattern tags inside the svg tag. Although, the console.log that we have when creating the patterns execute entirely.
What's wrong?
You need to set a height/width attribute on the pattern node:
defs.append("svg:pattern")
.attr("id", "circlePicture_" + d.name)
.attr("width", 12)
.attr("height", 12)
.append("svg:image")
...
Updated fiddle.

How can I dynamically update text labels in d3?

I want to add labels to my vertical bar chart that display the current percentage value that corresponds to the current hight of the bar.
So I need to continuously update the percentage value and I also need a transition to make the text element move insync with the bar chart.
I tried this:
var percentageLabels = svg.selectAll(".percentage-label")
.data(dataset);
percentageLabels.remove();
percentageLabels
.enter()
.append("text")
.attr("class", "percentage-label")
.style("fill", "white")
.text(function(d) {
return d;
})
.attr("y", function(d) {
return y(d);
})
.attr("x", function(d, i) {
return i * (w / dataset.length) + 2.5 / 100 * w + w * 10/100;
})
.transition().duration(1750).ease("linear")
.attr("y", function(d) {
return y(d);
});
Check out the fiddle
I'd make a couple changes here. First, wrap the rect and the text in a g, so you only need to data-bind once. Then you are free to transition them together:
var uSel = svg.selectAll(".input")
.data(dataset); //<-- selection of gs
uSel.exit().remove(); //<-- anybody leaving? remove g (both rect and text)
var gs = uSel
.enter()
.append("g")
.attr("class", "input"); //<-- enter selection, append g
gs.append("rect")
.attr("fill", "rgb(250, 128, 114)"); //<-- enter selection, rect to g
gs.append("text")
.attr("class", "percentage-label")
.style("fill", "white")
.attr("x", function(d, i) {
return i * (w / dataset.length) + 2.5 / 100 * w + w * 10/100;
}); //<-- enter selection, text to g
uSel.select("rect")
.attr("x", function(d, i) {
return i * (w / dataset.length) + 2.5 / 100 * w;
})
.attr("width", w / dataset.length - barPadding)
.attr("height", y(0))
.transition().duration(1750).ease("linear")
.attr("y", function(d) {
return y(d);
})
.attr("height", function(d) {
return h - y(d);
}); //<-- update rects with transition
uSel.select("text")
.transition().duration(1750).ease("linear")
.attr("y", function(d) {
return y(d);
})
.text(function(d) {
return d + "%";
}); //<-- update text with transition
Updated fiddle.
EDITS
To transition the text, you are probably going to have to use a custom tween function:
uSel.select("text")
.transition().duration(1750).ease("linear")
.attr("y", function(d) {
return y(d); //<-- move the text
})
.tween("", function(d) {
var self = d3.select(this),
oldValue = y.invert(self.attr("y")), //<-- get the current value
i = d3.interpolateRound(oldValue, d); //<-- interpolate to new value
return function(t) {
self.text(i(t) + '%') <-- update the text on each iteration
};
});
Updated, updated fiddle.
From the docs:
The transition.each method can be used to chain transitions and apply shared timing across a set of transitions. For example:
d3.transition()
.duration(750)
.ease("linear")
.each(function() {
d3.selectAll(".foo").transition()
.style("opacity", 0)
.remove();
})
.transition()
.each(function() {
d3.selectAll(".bar").transition()
.style("opacity", 0)
.remove();
});
You might want to check out this: https://github.com/mbostock/d3/wiki/Transitions#tween

D3 Javascript / SVG Part III ISsue

I'm following the part III tutorial of "Let' Make Some Charts" as an introduction to D3. Part of the tutorial calls for data insertion via TSV. Given I don't see this being an eventual use case for me, I'm attempting to modify the tutorial with the code below using a simple javascript array. However, nothing shows up on the page when I render in the browser. Can anyone shed some light on this?
Here's the tutorial link for some reference to the original code: http://bost.ocks.org/mike/bar/3/
My JS code:
<script>
var data = [4,8,15,16,23,42,57,89,100,160];
var width = 960,
height = 500; // have to make sure variables are case sensitive
var y = d3.scale.linear()
.domain([0, d3.max(data)]) // scaling based on max value
.range([height, 0]);
var chart = d3.select(".chart")
.attr("width", width)
.attr("height", height);
var barWidth = width / data.length;
var bar = chart.selectAll("g")
.data(data)
.enter().append("g")
.attr("transform", function(d,i) { return "translate(" + i * barWidth + ",0)";});
bar.append("rect")
.attr("y", function(d) { return y(d.value); })
.attr("width", barWidth - 1)
.attr("height", function(d) { return height - y(d.value); });
bar.append("text")
.attr("x", barWidth / 2)
.attr("y", function(d) { return y(d.value) + 3; })
.attr("dy", ".75em")
.text(function(d) { return d.value; });
function type(d) {
d.value = +d.value;
return d;
}
</script>
The code you've copied references a named attribute value to determine what to draw. The data you've created doesn't have this but just the data. So everywhere you have d.value, you need to reference just d.
Complete demo here.
Your problem stems from the fact that you're using an Array of numbers for your data, while in Mike Bostock's example he was using an Array of Objects (for example, var data = [{value: 30}, ...]). Thus you need to change all cases of d.value to d in your code, since your data is not longer an Object but just a number.
bar.append("rect")
.attr("y", function(d) { return y(d); }) // <---- delete .value
.attr("width", barWidth - 1)
.attr("height", function(d) { return height - y(d); }); // <---- delete .value
bar.append("text")
.attr("x", barWidth / 2)
.attr("y", function(d) { return y(d) + 3; }) // <---- delete .value
.attr("dy", ".75em")
.text(function(d) { return d; }); // <---- delete .value
Making these changes produces the following bar chart:

Fitting data for D3 graph to create legend

I have a data variable which contains the following:
[Object { score="2.8", word="Blue"}, Object { score="2.8", word="Red"}, Object { score="3.9", word="Green"}]
I'm interested in modifying a piece of a D3 graph http://bl.ocks.org/3887051 to display the legend, which would be the list of the "word", for my data set.
The legend script looks like this (from link above):
var ageNames = d3.keys(data[0]).filter(function(key) { return key !== "State"; });
var legend = svg.selectAll(".legend")
.data(ageNames.slice().reverse())
.enter().append("g")
.attr("class", "legend")
.attr("transform", function(d, i) { return "translate(0," + i * 20 + ")"; });
legend.append("rect")
.attr("x", width - 18)
.attr("width", 18)
.attr("height", 18)
.style("fill", color);
legend.append("text")
.attr("x", width - 24)
.attr("y", 9)
.attr("dy", ".35em")
.style("text-anchor", "end")
.text(function(d) { return d; });
How do I modify their ageNames function to display the "word" set from my data? I'm not sure how they're utilizing the d3.keys. Is there another way to do it?
This should work more or less, but you may need to reverse() (as the original example does) or otherwise rearrange the elements of words, in order to correctly map a word to the right color. Depends on how you've implemented your graph.
var words = yourDataArray.map(function(entry) { return entry.word; });
var legend = svg.selectAll(".legend")
.data(words)
// The rest stays the same

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