title: Different colors in ggplot2 using groups
body: <p>I have a problem trying to use different colors in my plot for two groups. I created a plot with odds ratios (including 95%CI) over a period of serveral years for 2 groups (mfin and ffin). When using the syntax below, all points and lines are black and my attempts to adjust them e.g. <code>geom_linerange(colour=c("red","blue"))</code> have failed (Error: Incompatible lengths for set aesthetics: colour).</p>
  
  <p><a href="https://i.stack.imgur.com/oKC9g.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/oKC9g.jpg" alt="enter image description here"></a></p>
  
  <p>Can anyone help me with this?</p>
  
  <pre><code>ggplot(rbind(data.frame(mfin, group=mfin), data.frame(ffin, group=ffin)), 
             aes(x = JAAR, y = ror, ymin = llror, ymax = ulror)) + 
  geom_linerange() + 
  geom_point() +
  geom_hline(yintercept = 1) + 
  ylab("Odds ratio &amp; 95% CI") + 
  xlab("") + 
  geom_errorbar(width=0.2)
  </code></pre>
  
  <p>Below are some sample data (1st group = mfin, @ND GROUP + ffin)</p>
  
  <p>JAAR    ror llror   ulror</p>
  
  <p>2008    2.00    1.49    2.51</p>
  
  <p>2009    2.01    1.57    2.59</p>
  
  <p>2010    2.06    1.55    2.56</p>
  
  <p>2011    2.07    1.56    2.58</p>
  
  <p>2012    2.19    1.70    2.69</p>
  
  <p>2013    2.23    1.73    2.72</p>
  
  <p>2014    2.20    1.71    2.69</p>
  
  <p>2015    2.31    1.84    2.78</p>
  
  <p>2016    .230    1.83    2.76</p>
  
  <p>JAAR    ror llror   ulror</p>
  
  <p>2008    1.36    0.88    1.84</p>
  
  <p>2009    1.20    0.73    1.68</p>
  
  <p>2010    1.16    0.68    1.64</p>
  
  <p>2011    1.23    0.77    1.69</p>
  
  <p>2012    1.43    1.00    1.86</p>
  
  <p>2013    1.46    1.04    1.88</p>
  
  <p>2014    1.49    1.07    1.90</p>
  
  <p>2015    1.30    0.89    1.70</p>
  
  <p>2016    1.29    0.89    1.70</p>