Develop Reference

Creating a categorical line chart in D3.js (V4)

I'm relatively new to D3.js and I'm visualising the 'PassengersIn' & 'PassengersOut' values from my busdatasimple.json file. For reference, one of the JSON objects looks like this;
{
"BusNo": "1",
"Date": "21 November 2016",
"Time": "09:10:34 AM",
"Destination": "Pier 50",
"Longitude": "-122.383262",
"Latitude": "37.773644",
"PassengersIn": "8",
"PassengersOut": "1"
}
I'm now trying to graph the PassengersIn & PassengersOut against the Destination using two lines on a line graph. I'm struggling with the axes as the x has only 2 ticks and the y is not scaling to my data. As seen below;
My code is as follows. I've removed the irrelevant Google Maps and jQuery.
//Setting The Dimensions Of The Canvas
var margin = {top: 20, right: 20, bottom: 70, left: 40},
width = 650 - margin.left - margin.right,
height = 350 - margin.top - margin.bottom;
//Setting X & Y Ranges
var x = d3.scaleOrdinal().range([0, width]);
var y = d3.scaleLinear().range([height, 0]);
//Define The Axes
var xAxis = d3.axisBottom().scale(x);
var yAxis = d3.axisLeft().scale(y).ticks(10);
//Add The SVG Element
var svg = d3.select("body").append("svg")
.attr("width", width + margin.left + margin.right + 50)
.attr("height", height + margin.top + margin.bottom + 200)
.attr("class", "svg")
.append("g")
.attr("transform", "translate(" + margin.left + "," + margin.top + ")");
//Load Data From JSON
d3.json("busdatasimple.json", function(error, data) {
//Functions for Y-Axis Grid Lines
function yGridLines() {
return d3.axisLeft().scale(y).ticks(5);
}
//Adding the Y-Axis Grid Lines
svg.append("g")
.attr("class", "grid-lines")
.call(yGridLines().tickSize(-width, 0, 0).tickFormat(""));
//Adding Y-Axis
svg.append("g")
.attr("class", "y axis").call(yAxis)
.append("text")
.attr("transform", "rotate(-90)")
.attr("y", 5)
.attr("dy", ".71em")
.style("text-anchor", "end")
.text("Passengers In");
//Adding X-Axis (Added to the end of the code so the label show over bottom bars)
svg.append("g")
.attr("class", "x axis")
.attr("transform", "translate(0," + height + ")")
.call(xAxis)
.selectAll("text")
.style("text-anchor", "middle")
//.attr("dx", "-.8em")
.attr("dy", "-.55em")
.attr("transform", "translate(-5, 15)")
.attr("font-family", "Arial")
.attr("font-weight", "bold")
.attr("font-size", "1.1em");
x.domain(data.map(function(d){return d.Destination;}));
y.domain([d3.min(data, function(d){return d.PassengersIn;}), d3.max(data, function(d) {return d.PassengersIn;})]);
var line = d3.line()
.x(function(d){return x(d.Destination);})
.y(function(d){return y(d.PassengersIn);});
svg.append("path").datum(data)
.attr("class", "line")
.attr("d", function(d){return d.PassengersIn;})
.attr("stroke", "green")
.attr("stroke-width", 2);
});
I've managed to find a few examples that use a categorical ordinal scale, however, they are all using v3 of d3.js and after reading through the v4 API countless times I still can't figure it out.

You want a categorical scale, that's right, but you don't want an ordinal scale here.
There was a lot of changes from v3 to v4. In v3, you could set .rangeBands, .rangeRoundBands, .rangePoints and .rangeRoundPoints to your ordinal scale, which therefore could accept an continuous range. Not anymore: in D3 v4 you have the brand new scaleBand and scalePoint.
In v4, in a regular ordinal scale (which is scaleOrdinal):
If range is specified, sets the range of the ordinal scale to the specified array of values. The first element in the domain will be mapped to the first element in range, the second domain value to the second range value, and so on. If there are fewer elements in the range than in the domain, the scale will reuse values from the start of the range. (emphases mine)
So, in an scaleOrdinal, the range need to have the same length (number of elements) of the domain.
That being said, you want a point scale (scalePoint) here. Band scales and point scales...
...are like ordinal scales except the output range is continuous and numeric. (emphasis mine)
Check this snippet, look at the console and compare the two scales:
var destinations = ["foo", "bar", "baz", "foobar", "foobaz"];
var scale1 = d3.scaleOrdinal()
.range([0, 100])
.domain(destinations);
var scale2 = d3.scalePoint()
.range([0, 100])
.domain(destinations);
destinations.forEach(d=>{
console.log(d + " in an ordinal scale: " + scale1(d) + " / in a point scale: " + scale2(d))
})
<script src="https://d3js.org/d3.v4.min.js"></script>
Regarding your y-axis problem:
Set the domain of the y scale before calling the axis. So, instead of this:
svg.append("g")
.attr("class", "y axis").call(yAxis);
y.domain([d3.min(data, function(d){
return d.PassengersIn;
}), d3.max(data, function(d){
return d.PassengersIn;
})]);
Change the order:
y.domain([d3.min(data, function(d){
return d.PassengersIn;
}), d3.max(data, function(d){
return d.PassengersIn;
})]);//set the domain first!
svg.append("g")
.attr("class", "y axis").call(yAxis);

D3 graph is missing as much text elements as there are ticks in axis

I experience the weirdest problem:
If I draw my axis before my graph, the graph misses as much text elements as there are ticks in the axis. When I increase or decrease the number of ticks, the number of missing text elements increases or decreases alike.
If I draw my axis after my graph, everything is alright.
I want to draw the axis first, as I want the grid lines to appear below the graph. And first of all, I want to understand what is going on here.
Here the code snippet in question:
var generateVisualization = function() {
var margin = {top: 30, right: 10, bottom: 30, left: 10};
var width = 1000 - margin.left - margin.right;
var height = (dataset.length * 11) + 5;
var xScale = d3.scale.linear()
.domain([1850, 2020])
.range([0, width])
var xAxisBottom = d3.svg.axis()
.scale(xScale)
.orient("bottom")
.tickSize(-height)
.tickFormat(d3.format("d")); // removes the comma as thousands separator
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 + ")")
// Axis drawn first
svg.append("g")
.attr("class", "x axis")
.attr("transform", "translate(0," + height + ")")
.call(xAxisBottom);
svg.selectAll("rect")
.data(dataset)
.enter()
.append("rect")
.attr("x", function(d, i) {
return xScale(d.BeginDate);
})
.attr("y", function(d, i) {
return i * 11 + 3;
})
.attr("width", function(d, i) {
return xScale(d.EndDate) - xScale(d.BeginDate);
})
.attr("height", 4)
.attr("class", "line");
svg.selectAll("text")
.data(dataset)
.enter()
.append("text")
.text(function(d) {
return d.DisplayName;
})
.attr("x", function(d, i) {
return xScale(d.BeginDate) + (xScale(d.EndDate) - xScale(d.BeginDate)) + 4;
})
.attr("y", function(d, i) {
return i * 11 + 8;
})
.attr("font-family", "sans-serif")
.attr("font-size", 8);
// Alternative: Axis drawn last
/*
svg.append("g")
.attr("class", "x axis")
.attr("transform", "translate(0," + height + ")")
.call(xAxisBottom);
*/
};

My hunch:
Instead of this:
svg.selectAll("text")
.data(dataset)
.enter()
.append("text")
.text(function(d) {
return d.DisplayName;
})
do this:
svg.selectAll(".myLabel")//selection via class
.data(dataset)
.enter()
.append("text")
.attr("class", "myLabel")//adding a class to the label
.text(function(d) {
return d.DisplayName;
})
Reason: when you do
svg.selectAll("text")
It will select the text on ticks, and bind the data to it. This is the reason for the anomaly... you increase the ticks the labels displayed decreases.
The above solution will add the class myLabel to only the labels but not the tick text, so the problem should resolve.

Unneeded white space before the 1st bar in D3 bar chart

I am trying to populate a data set into D3's Bar chart data. I am using this example from the d3: http://bl.ocks.org/mbostock/3885304
Here is my sample data:
var data = [{"name":"0","members_count":4},{"name":"1","members_count":1},{"name":"2","members_count":6},{"name":"3","members_count":1},{"name":"4","members_count":1},{"name":"5","members_count":2},{"name":"6","members_count":4},{"name":"7","members_count":3},{"name":"8","members_count":5},{"name":"9","members_count":1},{"name":"10","members_count":2},{"name":"11","members_count":3},{"name":"12","members_count":2},{"name":"13","members_count":0},{"name":"14","members_count":5},{"name":"15","members_count":2},{"name":"16","members_count":2},{"name":"17","members_count":4},{"name":"18","members_count":2},{"name":"19","members_count":4},{"name":"20","members_count":3},{"name":"21","members_count":5},{"name":"22","members_count":8},{"name":"23","members_count":3},{"name":"24","members_count":2},{"name":"25","members_count":3},{"name":"26","members_count":4},{"name":"27","members_count":4},{"name":"28","members_count":1},{"name":"29","members_count":1},{"name":"30","members_count":3},{"name":"31","members_count":5},{"name":"32","members_count":4},{"name":"33","members_count":3},{"name":"34","members_count":6},{"name":"35","members_count":2},{"name":"36","members_count":2},{"name":"37","members_count":7},{"name":"38","members_count":2},{"name":"39","members_count":4},{"name":"40","members_count":2},{"name":"41","members_count":1},{"name":"42","members_count":8},{"name":"43","members_count":10},{"name":"44","members_count":1},{"name":"45","members_count":5},{"name":"46","members_count":2},{"name":"47","members_count":5},{"name":"48","members_count":3},{"name":"49","members_count":1},{"name":"50","members_count":9},{"name":"51","members_count":3},{"name":"52","members_count":2},{"name":"53","members_count":8},{"name":"54","members_count":2},{"name":"55","members_count":3},{"name":"56","members_count":2},{"name":"57","members_count":2},{"name":"58","members_count":5},{"name":"59","members_count":1},{"name":"60","members_count":2},{"name":"61","members_count":4},{"name":"62","members_count":2},{"name":"63","members_count":2},{"name":"64","members_count":6},{"name":"65","members_count":6},{"name":"66","members_count":1},{"name":"67","members_count":1},{"name":"68","members_count":3},{"name":"69","members_count":5},{"name":"70","members_count":3},{"name":"71","members_count":4},{"name":"72","members_count":4},{"name":"73","members_count":1},{"name":"74","members_count":3},{"name":"75","members_count":2},{"name":"76","members_count":4},{"name":"77","members_count":5},{"name":"78","members_count":2},{"name":"79","members_count":1},{"name":"80","members_count":2},{"name":"81","members_count":1},{"name":"82","members_count":4},{"name":"83","members_count":3},{"name":"84","members_count":1},{"name":"85","members_count":4},{"name":"86","members_count":1},{"name":"87","members_count":3},{"name":"88","members_count":1},{"name":"89","members_count":8},{"name":"90","members_count":6},{"name":"91","members_count":6},{"name":"92","members_count":3},{"name":"93","members_count":4},{"name":"94","members_count":5},{"name":"95","members_count":2},{"name":"96","members_count":3},{"name":"97","members_count":2},{"name":"98","members_count":3},{"name":"99","members_count":6},{"name":"100","members_count":3},{"name":"101","members_count":1},{"name":"102","members_count":0},{"name":"103","members_count":5},{"name":"104","members_count":2},{"name":"105","members_count":1},{"name":"106","members_count":7},{"name":"107","members_count":1},{"name":"108","members_count":1},{"name":"109","members_count":7},{"name":"110","members_count":5},{"name":"111","members_count":5},{"name":"112","members_count":2},{"name":"113","members_count":6},{"name":"114","members_count":1},{"name":"115","members_count":2},{"name":"116","members_count":1},{"name":"117","members_count":1},{"name":"118","members_count":10},{"name":"119","members_count":2},{"name":"120","members_count":6},{"name":"121","members_count":1},{"name":"122","members_count":1},{"name":"123","members_count":2},{"name":"124","members_count":4},{"name":"125","members_count":5},{"name":"126","members_count":1},{"name":"127","members_count":1},{"name":"128","members_count":1},{"name":"129","members_count":3},{"name":"130","members_count":3},{"name":"131","members_count":3},{"name":"132","members_count":4},{"name":"133","members_count":3},{"name":"134","members_count":1},{"name":"135","members_count":5},{"name":"136","members_count":5},{"name":"137","members_count":1},{"name":"138","members_count":2},{"name":"139","members_count":5},{"name":"140","members_count":1},{"name":"141","members_count":1},{"name":"142","members_count":2},{"name":"143","members_count":2},{"name":"144","members_count":4},{"name":"145","members_count":4},{"name":"146","members_count":3},{"name":"147","members_count":5},{"name":"148","members_count":2},{"name":"149","members_count":1},{"name":"150","members_count":2},{"name":"151","members_count":3},{"name":"152","members_count":0},{"name":"153","members_count":3},{"name":"154","members_count":1},{"name":"155","members_count":2},{"name":"156","members_count":2},{"name":"157","members_count":1},{"name":"158","members_count":5},{"name":"159","members_count":4},{"name":"160","members_count":4},{"name":"161","members_count":5},{"name":"162","members_count":4},{"name":"163","members_count":2},{"name":"164","members_count":4},{"name":"165","members_count":2},{"name":"166","members_count":2},{"name":"167","members_count":1},{"name":"168","members_count":1},{"name":"169","members_count":10},{"name":"170","members_count":4},{"name":"171","members_count":2},{"name":"172","members_count":2},{"name":"173","members_count":1},{"name":"174","members_count":5},{"name":"175","members_count":1},{"name":"176","members_count":1},{"name":"177","members_count":5},{"name":"178","members_count":3},{"name":"179","members_count":1},{"name":"180","members_count":5},{"name":"181","members_count":8},{"name":"182","members_count":4},{"name":"183","members_count":2},{"name":"184","members_count":1},{"name":"185","members_count":3},{"name":"186","members_count":1},{"name":"187","members_count":3},{"name":"188","members_count":1},{"name":"189","members_count":1},{"name":"190","members_count":6},{"name":"191","members_count":4},{"name":"192","members_count":5},{"name":"193","members_count":1},{"name":"194","members_count":4},{"name":"195","members_count":2},{"name":"196","members_count":2},{"name":"197","members_count":2},{"name":"198","members_count":0},{"name":"199","members_count":3},{"name":"200","members_count":3},{"name":"201","members_count":1},{"name":"202","members_count":1},{"name":"203","members_count":1},{"name":"204","members_count":5},{"name":"205","members_count":1},{"name":"206","members_count":1},{"name":"207","members_count":1},{"name":"208","members_count":1},{"name":"209","members_count":1},{"name":"210","members_count":5},{"name":"211","members_count":2},{"name":"212","members_count":1},{"name":"213","members_count":5},{"name":"214","members_count":1},{"name":"215","members_count":3},{"name":"216","members_count":1},{"name":"217","members_count":1},{"name":"218","members_count":4},{"name":"219","members_count":2},{"name":"220","members_count":1},{"name":"221","members_count":3},{"name":"222","members_count":1},{"name":"223","members_count":3},{"name":"224","members_count":1},{"name":"225","members_count":2},{"name":"226","members_count":1},{"name":"227","members_count":1},{"name":"228","members_count":11},{"name":"229","members_count":9},{"name":"230","members_count":9},{"name":"231","members_count":9},{"name":"232","members_count":10},{"name":"233","members_count":10},{"name":"234","members_count":10},{"name":"235","members_count":9},{"name":"236","members_count":10},{"name":"237","members_count":10},{"name":"238","members_count":10},{"name":"239","members_count":10},{"name":"240","members_count":9},{"name":"241","members_count":9},{"name":"242","members_count":9},{"name":"243","members_count":10},{"name":"244","members_count":10},{"name":"245","members_count":9},{"name":"246","members_count":2},{"name":"247","members_count":1},{"name":"248","members_count":2},{"name":"249","members_count":2},{"name":"250","members_count":1},{"name":"251","members_count":2},{"name":"252","members_count":1},{"name":"253","members_count":5},{"name":"254","members_count":1},{"name":"255","members_count":1},{"name":"256","members_count":1},{"name":"257","members_count":1},{"name":"258","members_count":1},{"name":"259","members_count":1},{"name":"260","members_count":2},{"name":"261","members_count":1},{"name":"262","members_count":1},{"name":"263","members_count":2},{"name":"264","members_count":1},{"name":"265","members_count":1},{"name":"266","members_count":1},{"name":"267","members_count":1},{"name":"268","members_count":2},{"name":"269","members_count":2},{"name":"270","members_count":1},{"name":"271","members_count":1},{"name":"272","members_count":0},{"name":"273","members_count":2},{"name":"274","members_count":1},{"name":"275","members_count":2},{"name":"276","members_count":2},{"name":"277","members_count":1},{"name":"278","members_count":3},{"name":"279","members_count":1},{"name":"280","members_count":1},{"name":"281","members_count":1},{"name":"282","members_count":1},{"name":"283","members_count":1},{"name":"284","members_count":1},{"name":"285","members_count":1},{"name":"286","members_count":1},{"name":"287","members_count":1},{"name":"288","members_count":1},{"name":"289","members_count":1},{"name":"290","members_count":1},{"name":"291","members_count":1},{"name":"292","members_count":1},{"name":"293","members_count":1},{"name":"294","members_count":1},{"name":"295","members_count":1},{"name":"296","members_count":1},{"name":"297","members_count":2},{"name":"298","members_count":2},{"name":"299","members_count":1},{"name":"300","members_count":1},{"name":"301","members_count":1},{"name":"302","members_count":1},{"name":"303","members_count":1},{"name":"304","members_count":1},{"name":"305","members_count":1},{"name":"306","members_count":1},{"name":"307","members_count":1},{"name":"308","members_count":1},{"name":"309","members_count":1},{"name":"310","members_count":1},{"name":"311","members_count":1},{"name":"312","members_count":1},{"name":"313","members_count":0},{"name":"314","members_count":1}]
This is chart's drawing code.
var margin = {top: 20, right: 20, bottom: 30, left: 40},
width = (960 - margin.left - margin.right) * data.length/50,
height = 500 - margin.top - margin.bottom;
var x = d3.scale.ordinal()
.domain([0,1])
.rangeRoundBands([0, width], 0.1);
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")
.ticks(10, "%");
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 + ")");
x.domain(data.map(function(d) { return d.name; }));
y.domain([0, d3.max(data, function(d) { return d.members_count; })]);
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("fill","green")
.attr("x", function(d) { return x(d.name); })
.attr("width", x.rangeBand())
.attr("y", function(d) { return y(d.members_count); })
.attr("height", function(d) { return height - y(d.members_count); });
This issue I am getting is that I have some white space which looks ugly. This space come before the 1st bar and also after the last bar of the chart. I have tried tweaking the x value of the bar, But I think that is not a good way to do.
This space does not come when the data set is small. But when dataset is large then this space comes up. How can I remove this space from the start and from end.

The problem is with this line in scale:
.rangeRoundBands([0, width], 0.1);
When there is not specified the third parameter outerPadding it adds before and after the chart extra space produced by the padding parameter for each bar. You have set the padding to 0.1. To solve this problem set the outerPadding parameter:
var x = d3.scale.ordinal()
.domain([0,1])
.rangeRoundBands([0, width], 0.1, 0);
Here is updated your code: http://jsfiddle.net/ojntup1a/

d3 x-axis label positioned below the x-axis

I'm trying to draw an x-axis label for one of my d3 graphs, and I'm having a lot of trouble positioning it below the axis itself. Here is my current code:
svg.append("g")
.attr("class", "x axis")
.attr("transform", "translate(0," + height + ")")
.call(xAxis)
.append("text")
.attr("x", (width / 2))
.style("text-anchor", "middle")
.text("Users ordered by contribution");
And here is a screenshot of the problem. Is there a quick fix?

svg.append("g")
.attr("class", "x axis")
.attr("transform", "translate(0," + height + ")")
.call(xAxis)
.append("text")
.attr("x", (width / 2))
.attr("y", height) //set your y attribute here
.style("text-anchor", "middle")
.text("Users ordered by contribution");
You can set your y position attribute for your svg text as per above

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