Develop Reference

Creating a zoom function in D3

I have a function where that when a button is pressed (Several buttons the represent several animal types), that animal types SVG is updated with its corresponding data. I'm trying to replicate this zoom function but am having issues implementing it with my code. There are several SVGs that are used globally like this (one for each animal type):
let x = d3.scaleLinear()
.domain([0, 1000])
.range([ 0, width ]);
var xAxis = d3.axisBottom(x);
svgReptile.append("g")
.attr("transform", "translate(0," + height + ")")
.call(xAxis)
const yAxis = d3.scaleLinear()
.domain([0, 220])
.range([ height, 0])
svgReptile.append("g")
.call(d3.axisLeft(yAxis))
The function below is called when one of the animal buttons is pressed.
function update(animal, whatSVG, xAxis, yAxis, color) {
const points = whatSVG
.selectAll("circle")
.data(data);
points.enter()
.append("circle")
.attr("cx", function(d) {
return xAxis(d.state);
})
.attr("cy", function(d) {
return yAxis(d.percentage);
})
.merge(points)
.attr("r", 3)
.attr("cx", function(d) {
return xAxis(d.decade)
})
.attr("cy", function(d) {
return yAxis(d.count)
})
.style("fill", function (d) { return colour(d.animal) } );
points.exit()
.attr('r', 0)
.remove();
}
Question:
How can I implement a zoom feature that expands the x-axis when zoomed (or anything similar) like the one linked above?

I think you're looking for a 'brush zoom' from the last line of your question.
The following source code if from an example in a d3 graph gallery
The cross hair allows you to select an area to expand. If you follow the link there is a graph above it that is entitled "Zoom with axis" but it doesn't zoom in the way you've described, it just moves the axis, but doesn't enlarge the graph contents with it. Perhaps both will be useful!
Hope this helps
// set the dimensions and margins of the graph
var margin = {top: 10, right: 20, bottom: 20, left: 20},
width = 500 - margin.left - margin.right,
height = 400 - margin.top - margin.bottom;
// append the svg object to the body of the page
var Svg = d3.select("#brushZoom")
.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 + ")");
//Read the data
d3.csv("https://raw.githubusercontent.com/holtzy/D3-graph-gallery/master/DATA/iris.csv", function(data) {
// Add X axis
var x = d3.scaleLinear()
.domain([4, 8])
.range([ 0, width ]);
var xAxis = Svg.append("g")
.attr("transform", "translate(0," + height + ")")
.call(d3.axisBottom(x));
// Add Y axis
var y = d3.scaleLinear()
.domain([0, 9])
.range([ height, 0]);
Svg.append("g")
.call(d3.axisLeft(y));
// Add a clipPath: everything out of this area won't be drawn.
var clip = Svg.append("defs").append("svg:clipPath")
.attr("id", "clip")
.append("svg:rect")
.attr("width", width )
.attr("height", height )
.attr("x", 0)
.attr("y", 0);
// Color scale: give me a specie name, I return a color
var color = d3.scaleOrdinal()
.domain(["setosa", "versicolor", "virginica" ])
.range([ "#440154ff", "#21908dff", "#fde725ff"])
// Add brushing
var brush = d3.brushX() // Add the brush feature using the d3.brush function
.extent( [ [0,0], [width,height] ] ) // initialise the brush area: start at 0,0 and finishes at width,height: it means I select the whole graph area
.on("end", updateChart) // Each time the brush selection changes, trigger the 'updateChart' function
// Create the scatter variable: where both the circles and the brush take place
var scatter = Svg.append('g')
.attr("clip-path", "url(#clip)")
// Add circles
scatter
.selectAll("circle")
.data(data)
.enter()
.append("circle")
.attr("cx", function (d) { return x(d.Sepal_Length); } )
.attr("cy", function (d) { return y(d.Petal_Length); } )
.attr("r", 8)
.style("fill", function (d) { return color(d.Species) } )
.style("opacity", 0.5)
// Add the brushing
scatter
.append("g")
.attr("class", "brush")
.call(brush);
// A function that set idleTimeOut to null
var idleTimeout
function idled() { idleTimeout = null; }
// A function that update the chart for given boundaries
function updateChart() {
extent = d3.event.selection
// If no selection, back to initial coordinate. Otherwise, update X axis domain
if(!extent){
if (!idleTimeout) return idleTimeout = setTimeout(idled, 350); // This allows to wait a little bit
x.domain([ 4,8])
}else{
x.domain([ x.invert(extent[0]), x.invert(extent[1]) ])
scatter.select(".brush").call(brush.move, null) // This remove the grey brush area as soon as the selection has been done
}
// Update axis and circle position
xAxis.transition().duration(1000).call(d3.axisBottom(x))
scatter
.selectAll("circle")
.transition().duration(1000)
.attr("cx", function (d) { return x(d.Sepal_Length); } )
.attr("cy", function (d) { return y(d.Petal_Length); } )
}
})
<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/4.13.0/d3.min.js"></script>
<div id="brushZoom"></div>

D3 JS: How to add transition to refresh a plot when the dataset x-scale changes?

Looking at this Histogram chart using d3 example I plugged in my data but it had some strange side effects e.g. after refreshing to a new dataset, some information from the previous dataset i.e. x-axis scale was retained. I tried deleting and appending a new x-axis etc but nothing worked.
This happened due to the fact that my datasets had completely different x-axis ranges and scales. The only way I found to make it work was to select the whole svg element, remove it and re-append everything anew. However, this doesn't make a pleasant transition for the user so I was wondering how can this be improved to make it refreshable using transitions as in the original example even when having datasets with different x-scales and ranges.
This was my last approach which is a bit harsh to the eye:
// delete old
d3.select("#" + divId).select("svg").remove();
// then recreate all new
And this was my refresh attempt (integrated with AngularJS). Note how it has some common initialization and then if the SVG doesn't exist appends everything new otherwise tries to update it. I went bit by bit but can't see why the refresh doesn't remove all the previous dataset information of the x-axis scale:
var divId = $scope.histogramData.divId;
var color = $scope.histogramData.color;
var values = $scope.histogramData.data[$scope.histogramData.selected];
var svg = $scope.histogramData.svg;
// plot common initialization
var margin = {top: 40, right: 20, bottom: 20, left: 20},
width = 450 - margin.left - margin.right,
height = 370 - margin.top - margin.bottom;
var max = d3.max(values);
var min = d3.min(values);
var x = d3.scale.linear()
.domain([min, max])
.range([0, width]);
// generate a histogram using twenty uniformly-spaced bins.
var data = d3.layout.histogram()
.bins(x.ticks(10))
(values);
var yMax = d3.max(data, function(d){ return d.length });
var yMin = d3.min(data, function(d){ return d.length });
var colorScale = d3.scale.linear()
.domain([yMin, yMax])
.range([d3.rgb(color).brighter(), d3.rgb(color).darker()]);
var y = d3.scale.linear()
.domain([0, yMax])
.range([height, 0]);
var xAxis = d3.svg.axis()
.scale(x)
.orient("bottom");
// ===================================================================
// If the SVG doesn't exist then adds everything new
// ===================================================================
if (svg === undefined) {
var svg = d3.select("#" + divId)
.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 + ")");
$scope.histogramData.svg = svg;
var bar = svg.selectAll(".bar")
.data(data)
.enter()
.append("g")
.attr("class", "bar")
.attr("transform", function(d) { return "translate(" + x(d.x) + "," + y(d.y) + ")"; });
bar.append("rect")
.attr("x", 1)
.attr("width", (x(data[0].dx) - x(0)) - 1)
.attr("height", function(d) { return height - y(d.y); })
.attr("fill", function(d) { return colorScale(d.y) });
bar.append("text")
.attr("dy", ".75em")
.attr("y", -12)
.attr("x", (x(data[0].dx) - x(0)) / 2)
.attr("text-anchor", "middle")
.text(function(d) { return formatCount(d.y); });
var gTitle = svg.append("text")
.attr("x", 0)
.attr("y", 0 - (margin.top / 2))
.attr("text-anchor", "left")
.classed("label", true)
.text($scope.histogramData.spec[selected]);
$scope.histogramData.gTitle = gTitle;
var gAxis = svg.append("g")
.attr("class", "x axis")
.attr("transform", "translate(0," + height + ")")
.call(xAxis);
$scope.histogramData.gAxis = gAxis;
} else {
// ===================================================================
// If the SVG does exist then tries refreshing
// ===================================================================
var bar = svg.selectAll(".bar").data(data);
// remove object with data
bar.exit().remove();
bar.transition()
.duration(1000)
.attr("transform", function(d) { return "translate(" + x(d.x) + "," + y(d.y) + ")"; });
bar.select("rect")
.transition()
.duration(1000)
.attr("height", function(d) { return height - y(d.y); })
.attr("fill", function(d) { return colorScale(d.y) });
bar.select("text")
.transition()
.duration(1000)
.text(function(d) { return formatCount(d.y); });
var gTitle = $scope.histogramData.gTitle;
gTitle.transition()
.duration(1000)
.text($scope.histogramData.spec[selected]);
var gAxis = $scope.histogramData.gAxis;
gAxis.transition()
.duration(1000)
.call(xAxis);
}

I would suggest to keep this d3 code inside one angularJS directive and keep a watch on the json which you are using to plot that graph. As soon as values are changing the directive will be called again and the graph will be plotted. Hope it helps.

d3 axes not appearing

I'm having a problem getting the axes to actually show on my bar graph, so far without any luck as I just can't seem to wrap my head around what's wrong. Is it something to do with the scaling?
Is the axis rendering but being cut out of the svg by the bars?
<script type="text/javascript">
//Width and height
var w = 850;
var h = 650;
var barpadding = 20;
var dataset = [40, 99];
//Create SVG element
var svg = d3.select(".wrapper")
.append("svg")
.attr("width", w)
.attr("height", h);
//Create scale functions
var x = d3.scaleBand()
.range([0, w])
.padding(0.1);
var y = d3.scaleLinear()
.range([h, 0]);
svg.selectAll("rect")
.data(dataset)
.enter()
.append("rect")
.attr("x", function (d, i) {
return i * (w / dataset.length);
})
.attr("y", function (d) {
return h - (d * 4);
})
.attr("width", w / dataset.length - barpadding)
.attr("height", function (d) {
return d * 4;
})
.attr("fill", "dodgerblue");
svg.selectAll("text")
.data(dataset)
.enter()
.append("text")
.text(function (d) {
return d;
})
.attr("text-anchor", "middle")
.attr("x", function (d, i) {
return i * (w / dataset.length) + (w / dataset.length - barpadding) / 2;
})
.attr("y", function (d) {
return h - (d * 4) + 14;
})
.attr("font-family", "sans-serif")
.attr("font-size", "18px")
.attr("fill", "black");
d3.select(".axis")
.call(d3.axisBottom(x));
</script>

For showing the axis, you'll have to append a <g> element first. After that, since the axes are always generated at the origin (0,0), you'll have to translate it down and, only then, calling the axis:
svg.append("g")
.attr("class", "x axis")
.attr("transform", "translate(0," + someValue + ")")
.call(d3.axisBottom(x));
I normally provide a working demo, but this time I'll skip it, because your code has some problems:
It lacks the margins for the axis
It lacks the domains of the scales
It position the bars using magic numbers, not the scales
But, if you want to see your code with the axis 20px above the bottom, this is how it looks like: https://jsfiddle.net/qcnako3g/

rotate d3 horizontal bar graph to vertical bar graph [duplicate]

I have a vertical bar chart that is grouped in pairs. I was trying to play around with how to flip it horizontally. In my case, the keywords would appear on the y axis, and the scale would appear on the x-axis.
I tried switching various x/y variables, but that of course just produced funky results. Which areas of my code do I need to focus on in order to switch it from vertical bars to horizontal ones?
My JSFiddle: Full Code
var xScale = d3.scale.ordinal()
.domain(d3.range(dataset.length))
.rangeRoundBands([0, w], 0.05);
// ternary operator to determine if global or local has a larger scale
var yScale = d3.scale.linear()
.domain([0, d3.max(dataset, function (d) {
return (d.local > d.global) ? d.local : d.global;
})])
.range([h, 0]);
var xAxis = d3.svg.axis()
.scale(xScale)
.tickFormat(function (d) {
return dataset[d].keyword;
})
.orient("bottom");
var yAxis = d3.svg.axis()
.scale(yScale)
.orient("left")
.ticks(5);
var commaFormat = d3.format(',');
//SVG element
var svg = d3.select("#searchVolume")
.append("svg")
.attr("width", w + margin.left + margin.right)
.attr("height", h + margin.top + margin.bottom)
.append("g")
.attr("transform", "translate(" + margin.left + "," + margin.top + ")");
// Graph Bars
var sets = svg.selectAll(".set")
.data(dataset)
.enter()
.append("g")
.attr("class", "set")
.attr("transform", function (d, i) {
return "translate(" + xScale(i) + ",0)";
});
sets.append("rect")
.attr("class", "local")
.attr("width", xScale.rangeBand() / 2)
.attr("y", function (d) {
return yScale(d.local);
})
.attr("x", xScale.rangeBand() / 2)
.attr("height", function (d) {
return h - yScale(d.local);
})
.attr("fill", colors[0][1])
;
sets.append("rect")
.attr("class", "global")
.attr("width", xScale.rangeBand() / 2)
.attr("y", function (d) {
return yScale(d.global);
})
.attr("height", function (d) {
return h - yScale(d.global);
})
.attr("fill", colors[1][1])
;
sets.append("rect")
.attr("class", "global")
.attr("width", xScale.rangeBand() / 2)
.attr("y", function (d) {
return yScale(d.global);
})
.attr("height", function (d) {
return h - yScale(d.global);
})
.attr("fill", colors[1][1])
;

I just did the same thing last night, and I basically ended up rewriting the code as it was quicker than fixing all the bugs but here's the tips I can give you.
The biggest issues with flipping the x and y axis will be with things like return h - yScale(d.global) because height is calculated from the "top" of the page not the bottom.
Another key thing to remember is that when you set .attr("x", ..) make sure you set it to 0 (plus any padding for the left side) so = .attr("x", 0)"
I used this tutorial to help me think about my own code in terms of horizontal bars instead - it really helped
http://hdnrnzk.me/2012/07/04/creating-a-bar-graph-using-d3js/
here's my own code making it horizontal if it helps:
var w = 600;
var h = 600;
var padding = 30;
var xScale = d3.scale.linear()
.domain([0, d3.max(dataset, function(d){
return d.values[0]; })]) //note I'm using an array here to grab the value hence the [0]
.range([padding, w - (padding*2)]);
var yScale = d3.scale.ordinal()
.domain(d3.range(dataset.length))
.rangeRoundBands([padding, h- padding], 0.05);
var svg = d3.select("body")
.append("svg")
.attr("width", w)
.attr("height", h)
svg.selectAll("rect")
.data(dataset)
.enter()
.append("rect")
.attr("x", 0 + padding)
.attr("y", function(d, i){
return yScale(i);
})
.attr("width", function(d) {
return xScale(d.values[0]);
})
.attr("height", yScale.rangeBand())

An alternative is to rotate the chart (see this). This is a bit hacky as then you need to maintain the swapped axes in your head (the height is actually the width etc), but it is arguably simpler if you already have a working vertical chart.
An example of rotating the chart is below. You might need to rotate the text as well to make it nice.
_chart.select('g').attr("transform","rotate(90 200 200)");

Here is the procedure I use in this case:
1) Inverse all Xs and Ys
2) Remember that the 0 for y is on top, thus you will have to inverse lots of values as previous values for y will be inversed (you don't want your x axis to go from left to right) and the new y axis will be inversed too.
3) Make sure the bars display correctly
4) Adapt legends if there are problems
This question may help in the sense that it shows how to go from horizontal bar charts to vertical: d3.js histogram with positive and negative values

D3 bar char x-axis line not displaying

I am trying to draw a line in x-axis (bottom of bars in the chart) using the following script but it draws the on the top. What is the correct way of adding line on the bottom? Please help me to solve it.
var datasetBarChart = ${barList};
// set initial group value
var group = "All";
function datasetBarChosen(group) {
var ds = [];
for (x in datasetBarChart) {
if (datasetBarChart[x].group == group) {
ds.push(datasetBarChart[x]);
}
}
return ds;
}
function dsBarChartBasics() {
var margin = {top: 30, right: 5, bottom: 20, left: 50},
width = 1000 - margin.left - margin.right,
height = 450 - margin.top - margin.bottom,
colorBar = d3.scale.category20(),
barPadding = 1
;
return {
margin: margin,
width: width,
height: height,
colorBar: colorBar,
barPadding: barPadding
}
;
}
function dsBarChart() {
var firstDatasetBarChart = datasetBarChosen(group);
var basics = dsBarChartBasics();
var margin = basics.margin,
width = basics.width,
height = basics.height,
colorBar = basics.colorBar,
barPadding = basics.barPadding
;
var xScale = d3.scale.linear()
.domain([0, firstDatasetBarChart.length])
.range([0, width])
;
// Create linear y scale
// Purpose: No matter what the data is, the bar should fit into the svg area; bars should not
// get higher than the svg height. Hence incoming data needs to be scaled to fit into the svg area.
var yScale = d3.scale.linear()
// use the max funtion to derive end point of the domain (max value of the dataset)
// do not use the min value of the dataset as min of the domain as otherwise you will not see the first bar
.domain([0, d3.max(firstDatasetBarChart, function (d) {
return d.measure;
})])
// As coordinates are always defined from the top left corner, the y position of the bar
// is the svg height minus the data value. So you basically draw the bar starting from the top.
// To have the y position calculated by the range function
.range([height, 0])
;
//Create SVG element
var svg = d3.select("#barChart")
.append("svg")
.attr("width", width + margin.left + margin.right)
.attr("height", height + margin.top + margin.bottom)
.attr("id", "barChartPlot")
;
var plot = svg
.append("g")
.attr("transform", "translate(" + margin.left + "," + margin.top + ")")
;
var median = svg.append("line")
.attr("x2", width)
.attr("y2", (xScale/width))
.attr("stroke-width", 2)
.attr("stroke", "black");
plot.selectAll("rect")
.data(firstDatasetBarChart)
.enter()
.append("rect")
.attr("x", function (d, i) {
return xScale(i);
})
.attr("width", width / firstDatasetBarChart.length - barPadding)
.attr("y", function (d) {
return yScale(d.measure);
})
.attr("height", function (d) {
return height - yScale(d.measure);
})
.attr("fill", "lightgrey")
;
// Add y labels to plot
plot.selectAll("text")
.data(firstDatasetBarChart)
.enter()
.append("text")
.text(function (d) {
return formatAsInteger(d3.round(d.measure));
})
.attr("text-anchor", "middle")
// Set x position to the left edge of each bar plus half the bar width
.attr("x", function (d, i) {
return (i * (width / firstDatasetBarChart.length)) + ((width / firstDatasetBarChart.length - barPadding) / 2);
})
.attr("y", function (d) {
return yScale(d.measure) + 14;
})
.attr("class", "yAxis")
/* moved to CSS
.attr("font-family", "sans-serif")
.attr("font-size", "11px")
.attr("fill", "white")
*/
;
// Add x labels to chart
var xLabels = svg
.append("g")
.attr("transform", "translate(" + margin.left + "," + (margin.top + height) + ")")
;
xLabels.selectAll("text.xAxis")
.data(firstDatasetBarChart)
.enter()
.append("text")
.text(function (d) {
return d.category;
})
.attr("text-anchor", "middle")
// Set x position to the left edge of each bar plus half the bar width
.attr("x", function (d, i) {
return (i * (width / firstDatasetBarChart.length)) + ((width / firstDatasetBarChart.length - barPadding) / 2);
})
.attr("y", 15)
.attr("class", "xAxis")
//.attr("style", "font-size: 12; font-family: Helvetica, sans-serif")
;
// Title
svg.append("text")
.attr("x", (width + margin.left + margin.right) / 2)
.attr("y", 15)
.attr("class", "title")
.attr("text-anchor", "middle")
.text Breakdown 2015")
;
}
dsBarChart();
script for the line;
var median = svg.append("line")
.attr("x2", width)
.attr("y2", (xScale/width))
.attr("stroke-width", 2)
.attr("stroke", "black");

I don't quite understand your y2 attribute. It looks like you want the line to render as <line x1="0" y1="{height}" x2="{width}" y2="{height}" />
Ideally you want to express this in terms of your scale functions so if they change you won't have to update this statement. The corresponding d3 call for that would be:
var median = svg.append("line")
.attr("stroke-width", 2)
.attr("stroke", "black")
.attr("x1", xScale.range()[0])
.attr("x2", xScale.range()[1])
.attr("y1", yScale.range()[0])
.attr("y2", yScale.range()[0]);
Also, I think something is up with the xScale/width calculation. xScale is a function. Though you should look into d3.svg.axis too