title: How do I designate color levels in this crosstab visualization using ggplot?
body: <p>I'm trying to create a range of colors to reflect degrees of intensity in my crosstab plot. For example, values 0-33 get assigned light green, 34-66 get assigned a standard green, and 67-100 get assigned a forest green. I have only been able to figure out how to make the dots all one color. <strong>Is there a command to do this?</strong></p>
  
  <pre><code>#Load ggplot2
  library(ggplot2)                           
  
  #Specify foods and countries                         
  foods &lt;- c("popcorn", "carrots", "licorice", "eggs", "noodles", "walnuts")
  nations &lt;- c("Portgual", "Macedonia", "Germany", "France", "Denmark", "Belgium")
  
  #Create the data frame
  crosstab &lt;- expand.grid(foods, nations)
  crosstab$value &lt;- c(12.2, 5.4, 11.1, 33.1, 19.7, 6.5, 22.2, 21.1, 58.7, 91.4, 38.4, 14.0, 23.5, 34.2, 43.1, 51.5, 16.7, 19.1, 11.1, 28.9, 26.1, 14.1, 13.0, 41.2, 56.2, 32.1, 48.9, 47.3, 17.1, 46.5, 21.2,
                51.1, 62.1, 14.8, 53.5, 11.8)    
  
  #Plot the visualization
  final_plot &lt;- ggplot(crosstab, aes(Var1, Var2)) + geom_point(aes(size = value), colour = "lavender") + theme_bw() + xlab("") + ylab("")
  
  #Add design elements
  final_plot + scale_size_continuous(range = c(10, 25)) + geom_text(aes(label = value)) +
    theme(legend.position = "none") +
    theme(axis.text.x = element_text(size = 10)) +
    theme(axis.text.y = element_text(size = 10)) +
    theme(axis.ticks = element_blank()) +
    theme(panel.grid.major = element_blank(), panel.grid.minor = element_blank(),
            panel.background = element_blank())
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/cNU5K.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/cNU5K.png" alt="enter image description here"></a></p>