title: How to change legend title in ggplot
body: <p>I have the following plot like below. It was created with this command:</p>
  <pre><code>library(ggplot2)
  
  df &lt;- data.frame(cond = factor(rep(c(&quot;A&quot;, &quot;B&quot;), each = 200)), 
                   rating = c(rnorm(200), rnorm(200, mean=.8)))
  
  ggplot(df, aes(x=rating, fill=cond)) + 
  geom_density(alpha = .3) +
  xlab(&quot;NEW RATING TITLE&quot;) +
  ylab(&quot;NEW DENSITY TITLE&quot;)
  </code></pre>
  <p>Now, I want to modify the <em>legend title</em> from <strong>cond</strong> into <strong>NEW LEGEND TITLE</strong>.</p>
  <p>So, I just added the following line add the end of the above code:</p>
  <pre><code>+labs(colour=&quot;NEW LEGEND TITLE&quot;)
  </code></pre>
  <p>But it doesn't work. What's the right way to do it?</p>
  <p><img src="https://i.stack.imgur.com/sqpSU.png" alt="enter image description here" /></p>