title: Change colour scheme for ggplot geom_polygon in R
body: <p>I'm creating a map using the maps library and ggplot's geom_polygon. I'd simply like to change the default blue, red, purple colour scheme to something else. I'm extremely new to ggplot so please forgive if I'm just not using the right data types.  Here's what the data I'm using looks like:</p>
  
  <pre><code>&gt; head(m)
  region      long      lat group order subregion Group.1 debt.to.income.ratio.mean    ratio total
  17 alabama -87.46201 30.38968     1     1      &lt;NA&gt; alabama                   12.4059   20.51282    39
  18 alabama -87.48493 30.37249     1     2      &lt;NA&gt; alabama                   12.4059 20.51282    39
  19 alabama -87.52503 30.37249     1     3      &lt;NA&gt; alabama                   12.4059 20.51282    39
  20 alabama -87.53076 30.33239     1     4      &lt;NA&gt; alabama                   12.4059 20.51282    39
  21 alabama -87.57087 30.32665     1     5      &lt;NA&gt; alabama                   12.4059 20.51282    39
  22 alabama -87.58806 30.32665     1     6      &lt;NA&gt; alabama                   12.4059 20.51282    39
  
  &gt; head(v)
            Group.1 debt.to.income.ratio.mean    ratio     region total
  alabama       alabama                  12.40590 20.51282    alabama    39
  alaska         alaska                  11.05333 33.33333     alaska     6
  arizona       arizona                  11.62867 25.55556    arizona    90
  arkansas     arkansas                  11.90300  5.00000   arkansas    20
  california california                  11.00183 32.59587 california   678
  colorado     colorado                  11.55424 30.43478   colorado    92
  </code></pre>
  
  <p>Here's the code:</p>
  
  <pre><code>library(ggplot2)
  library(maps)
  
  states &lt;- map_data("state")
  m &lt;- merge(states, v, by="region")
  m &lt;- m[order(m$order),]
  
  p&lt;-qplot(long, lat, data=m, group=group, fill=ratio, geom="polygon")
  </code></pre>
  
  <p>I've tried the below and more:</p>
  
  <pre><code>cols &lt;- c("8" = "red","4" = "blue","6" = "darkgreen", "10" = "orange") 
  p + scale_colour_manual(values = cols)
  p + scale_colour_brewer(palette="Set1")
  p + scale_color_manual(values=c("#CC6666", "#9999CC"))
  </code></pre>