title: ggplot: how to use scale_fill_discrete and change colours without overriding the set scale
body: <p>My ggplot code looks like that:</p>
  <pre><code>t &lt;- ggplot(df, aes(fill= Faktor2, y=Analysis, x=Faktor)) + 
    geom_bar(position=&quot;stack&quot;, stat=&quot;identity&quot;, width = 0.4) +
    theme_bw() + ylab(&quot;Analysis&quot;) + xlab(&quot;Fator&quot;)+
    theme(axis.text.x = element_text(angle = 90, hjust = 1))+
    labs(fill =&quot;Other&quot;) +
    scale_fill_discrete(breaks = c(&quot;A&quot;, &quot;B&quot;, &quot;C&quot;, &quot;D&quot;,
                                            &quot;F&quot;, &quot;G&quot;))
  
  t + scale_fill_manual(values = mycolors)
  t + scale_fill_brewer(palette=&quot;Spectral&quot;)
  </code></pre>
  <p>I used scale_fill_discrete, so that certain items of my legend are removed.
  But now, when I change the color, the scales gets overwritten.
  I also tried it with the</p>
  <pre><code>scale_fill_hue function()
  </code></pre>
  <p>but that doesn't work either.</p>
  <p>I know it is better reproducible when I also provide you the data, but it is actually a kind of complex data, which merges several repetitions with an columns of an already existing one.</p>
  <p>So I hoped there is just one easy fix how I can adjust the colours using the scale_fill_discrete function.</p>
  <p>Thanks for any help</p>