title: changing the color palette in ggplot
body: <p>I have created ggplot from my data (sample below):</p>
  
  <p>I have created a violin plot of the <code>NKV</code> with the individual <code>NKV</code> data points plotted over it. I want to differentiate betweeen which <code>PID</code> my datapoints belong to. So far so good:</p>
  
  <pre><code>violin.murgang &lt;- ggplot(nkv.murgang, aes(x = factor("Murgang"), nkv.murgang$NK)) +
    geom_violin(color = "black", fill = "darkorange") + 
    ggtitle("NKV Murgang - Einfamilienhaus") + 
    labs(x = "Prozess", y = "Nutzen / Konsten \n Verhälhniss") +
    stat_summary(geom = "text", fun.y = quantile, 
                 aes(label=sprintf("%1.1f", ..y..)),
                 position=position_nudge(x=0.4), size=3) +
    theme (legend.position = "none") + 
    stat_summary(fun.data = give.n, geom = "text",  position=position_nudge(x=-0.4)) +
    geom_jitter(aes(col = PID ), width = 0.35) 
  violin.murgang
  </code></pre>
  
  <p>The problem is that all the <code>NKV</code> data points are only visualized in different shade of blue. I would like to have different colours. I have tried adding this: </p>
  
  <pre><code>  scale_colour_brewer(palette="Spectral")
  </code></pre>
  
  <p>which yields the error:</p>
  
  <pre><code>Error: Continuous value supplied to discrete scale
  </code></pre>
  
  <p>How can i achieve having different colour for the <code>geom_jitter</code> part?</p>
  
  <p>What causes the error?</p>
  
  <p>Thanks!</p>