Updating the D3 histogram as data arrives
SO community,
I am making a D3 histogram as an Angular directive and I want it to be able to change / update accordingly, like the data it reads in changes. In other words, I am using Angular to view changes in the data and (hopefully) redraw the histogram every time the data changes.
This is mainly a question about D3 update and data binding, because $ watchCollection works fine. Even though I went through this tutorial on adding items to d3 chart, I still cannot apply it on my histogram. I think the way the elements of my histogram are nested is really confusing me ...
Context: Ideally, this histogram will be read from an array that will hold the data returned from multiple Ajax calls. Thus, every time a new dataset arrives, the histogram will become another bar. That is why I would like to know how to properly update the chart as well as the x axis.
Thank!:)
The JS script is here: http://jsfiddle.net/santina/wrtenjny/1/
The code for just the d3 part is here, mostly from the mbostock sorting histogram.
// Aesthetic settings
var margin = {top: 20, right: 50, bottom: 20, left: 50},
width = document.getElementById('performance').clientWidth - margin.left - margin.right ||
940 - margin.left - margin.right,
height = 500 - margin.top - margin.bottom,
barColor = "steelblue",
axisColor = "whitesmoke",
axisLabelColor = "grey",
yText = "# QUERIES",
xText = "BEACON IDs";
// Inputs to the d3 graph
var data = scope[attrs.data];
// A formatter for counts.
var formatCount = d3.format(",.0f");
// Set the scale, separate the first bar by a bar width from y-axis
var x = d3.scale.ordinal()
.rangeRoundBands([0, width], .1, 1);
var y = d3.scale.linear()
.range([height, 0]);
var xAxis = d3.svg.axis()
.scale(x)
.orient("bottom");
var yAxis = d3.svg.axis()
.scale(y)
.orient("left")
.tickFormat(formatCount);
// Initialize histogram
var svg = d3.select(".histogram-chart")
.attr("width", width + margin.left + margin.right)
.attr("height", height + margin.top + margin.bottom)
.append("g")
.attr("transform", "translate(" + margin.left + "," + margin.top + ")");
function drawAxis(){
data.forEach(function(d) {
d.nqueries = +d.nqueries;
});
x.domain(data.map(function(d) { return d.name; }));
y.domain([0, d3.max(data, function(d) { return d.nqueries; })]);
// Draw x-axis
svg.append("g")
.attr("class", "x-axis")
.attr("transform", "translate(0," + height + ")")
.call(xAxis)
.append("text")
.attr("y", 6)
.attr("dy", "-0.71em")
.attr("x", width )
.style("text-anchor", "end")
.style("fill", axisLabelColor)
.text(xText);
// Draw y-axis
svg.append("g")
.attr("class", "y-axis")
.call(yAxis)
.append("text")
.attr("transform", "rotate(-90)")
.attr("y", 6)
.attr("dy", ".71em")
.style("text-anchor", "end")
.style("fill", axisLabelColor)
.text(yText);
// Change axis color
d3.selectAll("path").attr("fill", axisColor);
}
function updateAxis(){
console.log(data);
data.forEach(function(d) {
d.nqueries = +d.nqueries;
});
x.domain(data.map(function(d) { return d.name; }));
y.domain([0, d3.max(data, function(d) { return d.nqueries; })]);
svg.selectAll("g.y_axis").call(yAxis);
svg.selectAll("g.x_axis").call(xAxis);
}
function drawHistogram(){
drawAxis();
var bar = svg.selectAll(".bar")
.data(data)
.enter().append("g")
.attr("class", "barInfo");
bar.append("rect")
.attr("class", "bar")
.attr("x", function(d){ return x(d.name) })
.attr("width", x.rangeBand())
.attr("y", function(d){ return y(d.nqueries) })
.attr("height", function(d) { return height - y(d.nqueries); })
.attr("fill", barColor);
bar.append("text")
.attr("y", function(d){ return y(d.nqueries) })
.attr("x", function(d){ return x(d.name) })
.attr("dy", "-1px")
.attr("dx", x.rangeBand()/2 )
.attr("text-anchor", "middle")
.attr("class", "numberLabel")
.text(function(d) { return formatCount(d.nqueries); });
}
// Doesn't work :(
function updateHistogram(){
console.log("updating");
// Redefine scale and update axis
updateAxis();
// Select
var bar = svg.selectAll(".barInfo").data(data);
// Update - rect
var rects = bar.selectAll("rect")
.attr("class", "bar")
.attr("x", function(d){ return x(d.name) })
.attr("width", x.rangeBand());
// Update
var texts = bar.selectAll("text")
.attr("x", function(d){ return x(d.name) })
.attr("dx", x.rangeBand()/2 );
// Enter
bar.enter().append("g")
.attr("class", "bar").selectAll("rect").append("rect")
.attr("class", "bar")
.attr("x", function(d){ return x(d.name) })
.attr("width", x.rangeBand())
.attr("y", function(d){ return y(d.nqueries) })
.attr("height", function(d) { return height - y(d.nqueries); })
.attr("fill", barColor);
bar.enter().append("g")
.attr("class", "bar").selectAll("text").append("text")
.attr("y", function(d){ return y(d.nqueries) })
.attr("x", function(d){ return x(d.name) })
.attr("dy", "-1px")
.attr("dx", x.rangeBand()/2 )
.attr("text-anchor", "middle")
.attr("class", "numberLabel")
.text(function(d) { return formatCount(d.nqueries); });
}
drawHistogram();
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First, you got the wrong selector class
when updating the axis:
svg.selectAll("g.y-axis").call(yAxis); //<-- dash not underscore
svg.selectAll("g.x-axis").call(xAxis);
Second, you were close to your update, but we can clean it up a bit:
// select on what you originally binded data to
var bar = svg.selectAll(".barInfo").data(data);
// for data entering
var bEnter = bar.enter().append("g")
.attr("class", "barInfo");
// append a rect
bEnter.append("rect")
.attr("class", "bar");
// and the text elements
bEnter.append("text")
.attr("class","numberLabel");
// now we can update everybody together
bar.select("rect")
.attr("x", function(d){ return x(d.name) })
.attr("width", x.rangeBand())
.attr("y", function(d){ return y(d.nqueries) })
.attr("height", function(d) { return height - y(d.nqueries); })
.attr("fill", barColor);
bar.select("text")
.attr("y", function(d){ return y(d.nqueries) })
.attr("x", function(d){ return x(d.name) })
.attr("dy", "-1px")
.attr("dx", x.rangeBand()/2 )
.attr("text-anchor", "middle")
.attr("class", "numberLabel")
.text(function(d) { return formatCount(d.nqueries); });
A generalized example is here .
edits
Opps, I am not choosing my updates correctly.
bar.selectAll("rect")
Should be:
bar.select("rect")
This fixes both updates and sorting ...
Updated fiddle .
Also note that I have ruined your code again. With your angular chat, you don't really need a separate draw and update function, you can do both.
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