Maximum width for column in bar chart - d3.js

Question

I'm looking for a way of limiting the column width in a chart, I'm sure this ought to be relatively easy but I cant find a way of doing it.
I'm populating a chart from some dynamic data, where the number of columns can vary quite dramatically - between 1 and 20.
e.g: sample of csv
Location,Col1
"Your house",20
Location,Col1,Col2,Col3,Col4,Col5
"My House",12,5,23,1,5
This is working fine, and the col widths are dynamic, however when there is only one column in the data, I end up with one bar of width 756 (the whole chart), and I dont like the way this looks.
What I'd like to do is only ever have a maximum column of width 100px irrespective of the number of columns of data.
Below is my script for the chart
Many thanks,
<script>
var margin = {
top : 40,
right : 80,
bottom : 80,
left : 40
},
width = 960 - margin.left - margin.right,
height = 500 - margin.top - margin.bottom;
var x = d3.scale.linear().range([ 0, width ]);
var y = d3.scale.linear().range([ height, 0 ]);
var x0 = d3.scale.ordinal()
.rangeRoundBands([0, width], .05);
var x1 = d3.scale.ordinal();
var y = d3.scale.linear()
.range([height, 0]);
var chart = d3.select("body").append("svg")
.attr("class","chart")
.attr("width", width + margin.left + margin.right)
.attr("height", height + margin.top + margin.bottom)
.append("g")
.attr("transform", "translate(" + margin.left + "," + margin.top + ")");
var legendChart = d3.select("body").append("svg")
.attr("class","chart")
.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("/sampledata.csv.txt", function(error, data) {
// Use the first row of csv for header names
var reasonNames = d3.keys(data[0]).filter(function(key) {
return key !== "Location";
});
//console.log(reasonNames);
data.forEach(function(d) {
d.reasons = reasonNames.map(function(name) {
return {
name : name,
value : +d[name]
};
});
//console.log(d.reasons);
});
x0.domain(data.map(function(d) {return d.Location; }));
x1.domain(reasonNames).rangeRoundBands([0, x0.rangeBand()]);
console.log(x0.rangeBand());
y.domain([0, d3.max(data, function(d) { return d3.max(d.reasons, function(d) { return d.value; }); })]);
var maxVal = d3.max(data, function(d) { return d3.max(d.reasons, function(d) { return d.value; }); });
//console.log(maxVal);
var xAxis = d3.svg.axis()
.scale(x0)
.orient("bottom");
var yAxis = d3.svg.axis()
.scale(y)
.orient("left")
//.tickFormat(d3.format(".2s"));
chart.append("g")
.attr("class", "x axis")
.attr("transform", "translate(0," + height + ")")
.call(xAxis);
chart.append("g")
.attr("class", "y axis")
.call(yAxis);
var location = chart.selectAll(".name")
.data(data)
.enter().append("g")
.attr("class", "g")
.attr("transform", function(d) { return "translate(" + x0(d.Location) + ",0)"; });
location.selectAll("rect")
.data(function(d) { return d.reasons; })
.enter().append("rect")
.attr("width", x1.rangeBand()-2)
.attr("x", function(d) { return x1(d.name); })
.attr("y", function(d) { return y(d.value); })
.attr("height", function(d) { return height - y(d.value); })
.style("fill", function(d,i) { return "#"+3+"9"+i; /*color(d.name);*/ });
chart.selectAll("text")
.data(data)
.enter().append("text")
.attr("x", function(d) { return x1(d.name)+ x.rangeBand() / 2; })
.attr("y", function(d) { return y(d.value); })
.attr("dx", -3) // padding-right
.attr("dy", ".35em") // vertical-align: middle
.attr("text-anchor", "end") // text-align: right
.text("String");
var legend = legendChart.selectAll(".legend")
.data(reasonNames.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("x", 18)
.attr("width", 18)
.attr("height", 18)
.style("fill", function(d, i) {/*console.log(i);*/return "#" + 3 + "9" + i;
});
legend.append("text")
//.attr("x", width - 24)
.attr("x", 48)
.attr("y", 9).attr("dy",".35em")
//.style("text-anchor", "end")
//.text(function(d,i) { return String.fromCharCode((65+i))+i; });
.text(function(d) { return d; });
});
</script>

Answer 1

The easiest way to achieve this is by changing the line
.attr("width", x1.rangeBand()-2)
to
.attr("width", Math.min(x1.rangeBand()-2, 100))
You might also want to adjust the starting position and/or padding.

Answer 2

Code for adjusting starting position if anyone is stuck on it:
.attr("x", function(d, i) { return x1(d.seriesName) + (x1.rangeBand() - 100)/2 ;})
P.S. : referring answer from Lars.

Answer 3

Setting an absolute maximum width for the columns doesn't allow proper rendering for different screen resolutions, div sizes, etc.
In my case, I just wanted the columns not to look so large when the number of columns itself is small
I found it easier and more straight-forward to play with the scale definition, by changing the maximum width (where all columns will fit), their inner and outer paddings.
var w = 600
// var w = parseInt(d3.select(parentID).style('width'), 10) // retrieve the div width dynamically
var inner_padding = 0.1
var outer_padding = 0.8
var xScale = d3.scale.ordinal().rangeRoundBands([0, w], inner_padding, outer_padding)
When rendering the plot, I just ran a switch/if-else statement, which assigns different padding values. The lower the number of columns to plot, the greater the outer_padding (and eventually inner-padding) values I use.
This way, I keep the plots responsive.

Answer 4

I am able to change the width of the bar using the above answer. But unfortunately, my X Axis labels are not aligned when there is a single bar in the chart and it uses the max width set.
var tradeGroup = svg.selectAll("g.trade")
.data(trades)
.enter()
.append("svg:g")
.attr("class", "trade")
.style("fill", function (d, i) {
return self.color(self.color.domain()[i]);
})
.style("stroke", function (d, i) {
return d3.rgb(self.color(self.color.domain()[i])).darker();
});
var aWidth = Math.min.apply(null, [x.rangeBand(), 100]);
// Add a rect for each date.
var rect = tradeGroup.selectAll("rect")
.data(Object)
.enter()
.append("svg:rect")
.attr("x", function (d) {
return x(d.x);
})
.attr("y", function (d) { return y( (d.y || 0) + (d.y0 || 0)); })
.attr("height", function (d) { return y(d.y0 || 0) - y((d.y || 0) + (d.y0 || 0)); })
.attr("width", Math.min.apply(null, [x.rangeBand(), 100]));

Answer 5

For completeness the full answer would look like this:
svg.selectAll(".bar")
.data(data)
.enter().append("rect")
.attr("class", "bar")
.attr("x", (d) -> x1(d.name) + (x1.rangeBand() - d3.min([x1.rangeBand(), 100]))/2)
.attr("width", d3.min([x1.rangeBand(), 100]))
.attr("y", (d) -> y(d.grade) )
.attr("height", (d)-> height - y(d.value) )
(coffeescript syntax)
Note this include the full answer, the 'width' and the 'x' settings. Also 'x' settings is accounting for a when 100 width is not the min value.

Answer 6

Thought I'd share that I came up with a slightly different answer to this. I didn't want to hard code in a maximum bar width because 1) it wasn't responsive to different screen sizes and 2) it also required playing with the x-coordinate attribute or accepting some irregular spacing.
Instead, I just set a minimum number of bars, based on the point where the bars became too wide (in my case, I found that less than 12 bars made my chart look weird). I then adjusted the scaleBand's range attribute, proportionately, if there were less than that number of bars. So, for example, if the minimum was set to 12 and there were only 5 items in the data, rather than rendering each of them at 1/5th of the full width, I scaled the range down to 5/12ths of the original width.
Basically, something like this:
// x is a scaleBand() that was previously defined, and this would run on update
var minBarSlots = 12;
if (data.length < minBarSlots) {
x.range([0, width*(data.length/minBarSlots)])
}
else {
x.range([0, width])
}`