d3.js nvd3.js — Get y-axis min/max values

Question

I'm using NVD3's lineChart model.

I need to force-set the min and max y-axis values relative to the actual ones, e.g.:

chart.lines.forceY([min/1.1,max*1.1]);

How can I get the current min/max y-axis values?

Fretwork

Answer 1

You can get the current domain through chart.yAxis.scale().domain().

Lampyrid

I don't need the domain, but the exact min and max values. In my case chart.yAxis.scale().domain() returns an array: [0, 1] – Fretwork

For this, you can use d3.extent on your data. – Lampyrid

Yes, I can always get the min and max values from the data but it will be a reduntant calculation. I'm asking if there is a way to query the values directly from the chart object as they are already calculated. – Fretwork

Not unless they're set as the domain of the scale. – Lampyrid

They are not set as the domain. – Fretwork

Then you'll have to recalculate them. – Lampyrid

Answer 2

If you have already set the y-axis domain like so:

var yAxis = d3.svg.axis().scale(y)
    .orient("left").ticks(5);

y.domain([0, d3.max(yourData)]);

you can access the values through y. y[0] is the minimum, y[1] is the max.

Hemistich

This is the correct answer. Try also: d3.extent(y.domain()) to return both the lower bound and upper bound values on the y-axis in a simple array. – Propose

Addendum: Once the bounded values are known, you can simply use y(min) or y(max) to get the mapped bounds for your specified range. – Propose