First define the margin
object with properties for the four sides (clockwise from the top, as in CSS).
var margin = {top: 20, right: 10, bottom: 20, left: 10};
Then define width
and height
as the inner dimensions of the chart area.
var width = 960 - margin.left - margin.right,
height = 500 - margin.top - margin.bottom;
Lastly, define svg
as a G element that translates the origin to the top-left corner of the chart area.
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 + ")");
With this convention, all subsequent code can ignore margins. For example, to create x and y scales, simply say:
var x = d3.scale.linear()
.range([0, width]);
var y = d3.scale.linear()
.range([height, 0]);
If you want to add axes to the chart, they will be positioned correctly by default in the "left" and "top" orientations. For "right" or "bottom" orientation, translate the axis G element by the width or height, respectively.