Develop Reference

D3.js -- How do I update dataset via Javascript?

I have a dataset with 11 different variables (csv file with 12 columns). I want to be able to select a certain column for my scatterplot, but I'm having some difficulties. Please bear with me, as JavaScript is not my strong suit (obviously). Here's what I attempted:
<div class="variables" id="fixedacidity" onclick="drawPlot('fixedacidity');">
<h1>fixed acidity</h1>
</div>
<div class="variables" id="volatileacidity" onclick="drawPlot('volatileacidity');">
<h1>volatile acidity</h1>
</div>
<div class="variables" id="citricacid" onclick="drawPlot('citricacid');">
<h1>citric acid</h1>
</div>
<div class="variables" id="residualsugar" onclick="drawPlot('residualsugar');">
<h1>residual sugar</h1>
</div>
etc ...
I made a simple menu that calls on the drawPlot function, but I'm having trouble trying to get the variable to pass on correctly.
Relevant d3/javascript:
function drawPlot(selectedVar){
$(".visarea").html("");
var wineVar = selectedVar;
var margin = {top: 20, right: 20, bottom: 30, left: 40},
width = 860 - margin.left - margin.right,
height = 350 - margin.top - margin.bottom;
var x = d3.scale.linear()
.range([0, width]);
var y = d3.scale.linear()
.range([height, 0])
.domain([0,10]);
var color = d3.scale.category10();
var xAxis = d3.svg.axis()
.scale(x)
.orient("bottom");
var yAxis = d3.svg.axis()
.scale(y)
.orient("left").ticks(10);
var chart1 = d3.select(".visarea").append("svg")
.attr("width", width + margin.left + margin.right)
.attr("height", height + margin.top + margin.bottom)
.append("g")
.attr("transform", "translate(" + margin.left + "," + margin.top + ")");
d3.csv("red.csv", function(error, data) {
if (error) throw error;
data.forEach(function(d) {
d.wineVar = +d.wineVar;
d.quality = +d.quality;
});
x.domain(d3.extent(data, function(d) { return d.wineVar; })).nice();
y.domain([0,10]).nice();
chart1.append("g")
.attr("class", "x axis")
.attr("transform", "translate(0," + height + ")")
.call(xAxis)
.append("text")
.attr("class", "label")
.attr("x", width)
.attr("y", -6)
.style("text-anchor", "end")
.text(wineVar);
chart1.append("g")
.attr("class", "y axis")
.call(yAxis)
.append("text")
.attr("class", "label")
.attr("transform", "rotate(-90)")
.attr("y", 6)
.attr("dy", ".71em")
.style("text-anchor", "end")
.text("Rated Quality")
chart1.selectAll(".red.dot")
.data(data)
.enter().append("circle")
.attr("class", "red dot")
.attr("r", 3)
.attr("cx", function(d) { return x(d.wineVar); })
.attr("cy", function(d) { return y(d.quality); })
.style("fill", "red");
});
}
Although the variable gets passed on to the function, d.wineVar, as expected, does not return the desired value, and thus the chart does not draw the correct values. Can anyone recommend a workaround for this? It seems so simple, yet I've spent hours failing trying to figure this out.
Sample of red.csv:
fixedacidity,volatileacidity,citricacid,residualsugar,chlorides,freesulfurdioxide,totalsulfurdioxide,density,pH,sulphates,alcohol,quality
7.4,0.7,0,1.9,0.076,11,34,0.9978,3.51,0.56,9.4,5
7.8,0.88,0,2.6,0.098,25,67,0.9968,3.2,0.68,9.8,5
7.8,0.76,0.04,2.3,0.092,15,54,0.997,3.26,0.65,9.8,5
Image of what I'm trying to accomplish. The first dataset, fixedacidity, gets drawn up fine. I'm having difficulties trying to get the menu to correctly show its respective dataset. "Rated Quality" will always be the data for the Y-axis.

You has wrong variable reference, here:
data.forEach(function(d) {
d.wineVar = +d.wineVar; // <---------Here
d.quality = +d.quality;
});
change by:
data.forEach(function(d) {
d.wineVar = +d[wineVar]; // <----------Here
d.quality = +d.quality;
});

There is the obvious issue pointed out by klaujesi about data extraction. But there are more issues with your code.
I would say you need to adapt your approach to the way d3.js works. Currently you will add a new svg on each call to the function, caused by this line in your code: d3.select(".visarea").append("svg")
I usually have some init code wrapped in one function, which creates the svg and sets ups everything static. Then there is an update function which will handle input changes to show different data, use different scales etc.
The nice thing about d3.js is that you can control very easily what's to happen with newly introduced data via .enter() and removed data via .exit().

array to map ordinal y-axis d3

I am trying to develop a scatterplot using d3 but the domain for y-axis is confusing me. y-axis are gonna display patient names and x-axis display their appointment dates. x-axis are working fine, but y-axis are displaying only two patient names.
function graph() {
var num_patient = Object.keys(patientList).length;
var patient_names = Object.keys(patientList);
console.log(patient_names);
var x = d3.time.scale().range([0, width]);
var y = d3.scale.ordinal().range([height, 0]);
x.domain(d3.extent(data, function(d) {return parseDate(d.dates); }));
//y.domain(patient_names.map(function(d) { return d.name;}));
y.domain(patient_names);
console.log(y.domain());
var xAxis = d3.svg.axis()
.scale(x)
.ticks(d3.time.year, 1)
.orient("bottom");
var yAxis = d3.svg.axis()
.scale(y)
.orient("left");
var svg = d3.select("#punchcard")
.append("svg")
.attr("width", width + margin.left + margin.right)
.attr("height", height + margin.top + margin.bottom)
.append("g")
.attr("transform", "translate(" + margin.left + "," + margin.top + ")");
svg.selectAll("dot")
.data(data)
.enter()
.append("circle")
.attr("r", 3.5)
.attr("cx", function(d) { return x(d.date); })
.attr("cy", function(d) { return y(d.value); });
svg.append("g") // Add the X Axis
.attr("class", "x axis")
.attr("transform", "translate(0," + height + ")")
.call(xAxis);
svg.append("g") // Add the Y Axis
.attr("class", "y axis")
.call(yAxis);
}
console.log(patient_names) display the names correctly:
`["Andrew","Fred","Steve","John"]`
console.log(y.domain()) displays an extra undefined object:
["Andrew", "Fred","Steve" , "John", undefined]
But the y-axis only display Andrew at 0 and Fred at height h. How can I get to display all four names? I cannot hard code them as they are user input values. BTW: I am a beginner with d3 and js.
Thanks in advance!

With ordinal scales, you need to define the range points for the inputs explicitly (see the documentation). That is, you need to tell the scale explicitly which input value to map to which output. For example:
var y = d3.scale.ordinal()
.domain(["Andrew","Fred","Steve","John"])
.range([height, height * 2/3, height * 1/3, 0]);
You probably want to use the .rangePoints() method instead, which allows you to specify an interval that D3 automatically divides based on the number of values in the domain:
var y = d3.scale.ordinal()
.domain(["Andrew","Fred","Steve","John"])
.rangePoints([height, 0]);
Note that for .rangePoints() to work properly, you need to set the domain before the output range.

D3 charts - Data overlapping issue with huge data

I have generated a bar chart using D3 charts. Here is the js code
function renderChart(filename) {
var margin = {top: 20, right: 20, bottom: 30, left: 40},
width = 960 - margin.left - margin.right,
height = 500 - margin.top - margin.bottom;
//var formatPercent = d3.format(".0%");
var x = d3.scale.ordinal()
.rangeRoundBands([0, width], .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");
var svg = d3.select("body").append("svg")
.attr("width", width + margin.left + margin.right)
.attr("height", height + margin.top + margin.bottom)
.append("g")
.attr("transform", "translate(" + margin.left + "," + margin.top + ")");
var data = [
{"name": "india", "population": 120},
{"name": "uk", "population": 200},
{"name": "us", "population": 300},
{"name": "china", "population": 50}
];
x.domain(data.map(function(d) { return d.name; }));
y.domain([0, d3.max(data, function(d) { return d.population; })]);
svg.append("g")
.attr("class", "x axis")
.attr("transform", "translate(0," + height + ")")
.call(xAxis);
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")
.text("Frequency");
svg.selectAll("bar")
.data(data)
.enter().append("rect")
.attr("class", "bar")
.attr("x", function(d) { return x(d.name); })
.attr("width", x.rangeBand())
.attr("y", function(d) { return y(d.population); })
.attr("height", function(d) { return height - y(d.population); });
}
Here is the link to fiddle - http://jsfiddle.net/scfx9/
Here, the width of the bars increases and decreases according to the size of the data. When ever I pass huge data the bars shrink and data gets overlapped as the div size is fixed. How do I make the size of the bars constant and allow the users to use the arrow keys to move the data as in the example below
http://bl.ocks.org/mbostock/4062085

If you look at the example you posted, he is handling the keydown event for arrow keys:
d3.select(window).on("keydown", function() {
switch (d3.event.keyCode) {
case 37: year = Math.max(year0, year - 10); break;
case 39: year = Math.min(year1, year + 10); break;
}
update();
});
Your data will need to work a little bit differently but the concept of windowing is the same. Each time the arrow key is pressed your handler will produce a data array that represents the current window into the overall data. Then you will bind the array to enter new bars and exit old ones and you can decide the kind of transition you want.
One difference in your case compared with the example is that his example uses a fixed scale on his X axis, so he never needs to change the axis. In your case because you're using an ordinal scale and your values will be different for each data window, you'll need to update the domain on your X scale and redraw the axis (possible in a transition if you like).

x-axis zooming with d3 line charts

I'm just getting into using d3, and relatively novice in js still. I'm trying to set up a page of log file visualizations for monitoring some servers. Right now I'm focusing on getting a line chart of CPU utilization, where I can focus on specific time periods (So an x-zoom only). I am able to do a static charts easily, but when it comes to the zooming the examples are going over my head and I can't seem to make them work.
This is the static example I followed to get things up and running, and this is the zoom example I've been trying to follow.
My input csv is from a rolling set of log files (which will not be labled on the first row), each row looks like this:
datetime,server,cpu,memory,disk,network_in,network_out
So far what I've been able to get on the zoom looks like this:
var parseDate = d3.time.format("%Y-%m-%d %H:%M:%S").parse;
// define dimensions of graph
var margin = {top: 20, right: 80, bottom: 30, left: 50},
width = 960 - margin.left - margin.right,
height = 200 - margin.top - margin.bottom;
var x = d3.time.scale().range([0, width]);
var y = d3.scale.linear().range([height, 0]);
var xAxis = d3.svg.axis()
.scale(x)
.orient("bottom")
.tickSize(-height, 0)
.tickPadding(6);
var yAxis = d3.svg.axis()
.scale(y)
.orient("left")
.tickSize(-width)
.tickPadding(6);
// Define how we will access the information needed from each row
var line = d3.svg.line()
.interpolate("step-after")
.x(function(d) { return x(d[0]); })
.y(function(d) { return y(d[2]); });
// Insert an svg element into the document for each chart
svg = d3.select("body").append("svg")
.attr("width", width + margin.left + margin.right)
.attr("height", height + margin.top + margin.bottom)
.append("g")
.attr("transform", "translate(" + margin.left + "," + margin.top + ")");
// Declare zoom handler
var zoom = d3.behavior.zoom().on("zoom", draw);
// Open the log and extract the information
d3.text("log.csv", function(text) {
var data = d3.csv.parseRows(text).map(function(row) {
return row.map(function(value, index) {
if (index == 0) {
return parseDate(value);
}
else if (index > 1) {
return +value;
}
else {
return value;
}
});
});
// Set the global minimum and maximums
x.domain(d3.extent(data, function(d) { return d[0]; }));
y.domain(d3.extent(data, function(d) { return d[2]; }));
zoom.x(x);
// Finally, we have the data parsed, and the parameters of the charts set, so now we
// fill in the charts with the lines and the labels
svg.append("g")
.attr("class", "x axis")
.attr("transform", "translate(0," + height + ")")
.call(xAxis);
svg.append("g")
.attr("class", "y axis")
.call(yAxis)
.append("text")
.attr("transform", "rotate(-90)")
.attr("y", 6)
.attr("dy", ".71em")
.attr("text-anchor", "end")
.text("Percent (%)");
svg.append("path")
.datum(data)
.attr("class", "line")
.attr("d", line);
svg.append("text")
.attr("x", margin.left)
.attr("y", 0 - (margin.top / 2))
.attr("text-anchor", "middle")
.text('all');
svg.append("rect")
.attr("class", "pane")
.attr("width", width)
.attr("height", height)
.call(zoom);
svg.select("path.line").data([data]);
draw();
});
function draw() {
svg.select("g.x.axis").call(xAxis);
svg.select("g.y.axis").call(yAxis);
svg.select("path.line").attr("d", line);
}
What this gives me is a very sluggish chart that can be zoomed and panned, but it does not clip off the line at the ends of the chart. I've tried adding in the clipping elements described in the example, but that ends up fully erasing my line every time.
Thanks for any help or direction

Dynamically update chart data in D3

I'm working on a real-time visualization of incoming data. I use D3 for the visualization and started based on this example: http://bl.ocks.org/mbostock/3883195
This is the version I'm currently working on:
var margin = {top: 20, right: 20, bottom: 30, left: 50},
width = 500 - margin.left - margin.right,
height = 300 - margin.top - margin.bottom;
var x = d3.time.scale().range([0, width]);
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");
var area = d3.svg.area()
.x(function(d) { return x(d.x); })
.y0(height)
.y1(function(d) { return y(d.y); });
var svg = d3.select("div#chart").append("svg")
.attr("width", width + margin.left + margin.right)
.attr("height", height + margin.top + margin.bottom)
.append("g")
.attr("transform", "translate(" + margin.left + "," + margin.top + ")");
var data = [[1,1],[2,3],[3,2],[4,4]];
var dataCallback = function(d) {
d.x = +d[0];
d.y = +d[1];
};
data.forEach(dataCallback);
x.domain(d3.extent(data, function(d) { return d.x; }));
y.domain([0, d3.max(data, function(d) { return d.y; })]);
svg.append("path")
.datum(data)
.attr("class", "area")
.attr("d", area);
svg.append("g")
.attr("class", "x axis")
.attr("transform", "translate(0," + height + ")")
.call(xAxis);
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")
.text("Number of Messages");
This produces the following graph:
Now, as it should update itself regularly, I wanted to dynamically update the data in the graph using the following code:
var n = svg.selectAll("path").data([5,20])
n.enter();
n.exit().remove();
However, that does not work. I'm new to D3 and still learning the basics. Ideally, the graph visualization shifts to the left and the new data is shown in the graph. But so far I can't even add new data to it. Could someone help me with that? I also searched for examples similar to this, but did not found anything which really helped me so far.

d3 is pretty good at keeping track of what data's been added and what's being removed - it does this with joins. Take a look at http://bl.ocks.org/mbostock/3808218
IF we use the data binding (instead of "datum")
svg.append("path")
.data([data])
.attr("class", "area")
.attr("d", area);
and then on update do something like:
// update the list of coordinates
data.splice(0,1);
data.push([5,20]);
// re-decorate the last, newly added item
dataCallback(data[data.length - 1]);
// You will also need to update your axes
x.domain(d3.extent(data, function(d) { return d.x; }));
y.domain([0, d3.max(data, function(d) { return d.y; })]);
// update the data association with the path and recompute the area
svg.selectAll("path").data([data])
.attr("d", area);
And you should get your area to update.
You can try it out here
With the way your data is organized using the joined data (instead of datum) may not make much difference. Note that here the (single) data element you are associating with the path is the full list of coordinates so to update the area you need to pass in a new full list of coordinates.
If you really want to minimized the amount you need to redraw you could break up the area and draw each line segment. Then essentially you fall back to the bar chart example but with not-flat bars and no spacing.