title: D3 grouped bar chart: How to rotate the text of x axis ticks?
body: <p>I'm using the Grouped Bar Chart(<a href="http://bl.ocks.org/mbostock/3887051" rel="noreferrer">http://bl.ocks.org/mbostock/3887051</a>), but the text of the x-axis is very long, as shown in attached picture. How to rotate the text? Thank you. <img src="https://i.stack.imgur.com/ed3ZU.png" alt="enter image description here"> </p>