title: How can I add three bars to each spot on the Y axis of a plot
body: <p>I have a significant three-way interaction that I would like to plot. The three factors are Collection, Variety, and Irrigation, and the response variable is meanGlucCVI. My current idea (open to other suggestions) is to have a bar graph with the meanGlucCVI response on the Y axis and Irrigation on the X axis. At each Irrigation treatment on the X axis, there would be a bar for each Collection treatment. Finally, I would make one of these graphs for each Variety.</p>
  
  <p>My issue is that I don't know how to add the three collection bars into my plots. I've seen graphs that look like this plenty of times, but I'm not solid enough with R to make it happen.</p>
  
  <p>Does this seem like a sensible way to show this data? If so, how could I write code for it? I think that using <code>ggplot</code> and its <code>facetwrap</code> function might make sense, or maybe just using <code>ggplot</code> for the individual graphs and combining them with <code>gridExtra</code> from base R (if that's possible.)</p>
  
  <p>Here is my current dataset:</p>
  
  <pre><code>dput(head(dataAvgGlucCVI))
  
  
  structure(list(Collection = structure(c(1L, 1L, 1L, 1L, 1L, 1L
  ), .Label = c("1", "2", "3"), class = "factor"), Variety = structure(c(1L, 
  1L, 1L, 1L, 1L, 2L), .Label = c("Hodag", "Lamoka", "Snowden"), class = "factor"), 
      Irrigation = structure(c(1L, 2L, 3L, 4L, 5L, 1L), .Label = c("Rate1", 
      "Rate2", "Rate3", "Rate4", "Rate5"), class = "factor"), meanGlucCVI = c(0.03475, 
      0.03475, 0.0455, 0.047, 0.061, 0.04275)), row.names = c(NA, 
  -6L), groups = structure(list(Collection = structure(c(1L, 1L
  ), .Label = c("1", "2", "3"), class = "factor"), Variety = structure(1:2, .Label = c("Hodag", 
  "Lamoka", "Snowden"), class = "factor"), .rows = list(1:5, 6L)), row.names = c(NA, 
  -2L), class = c("tbl_df", "tbl", "data.frame"), .drop = TRUE), class = c("grouped_df", 
  "tbl_df", "tbl", "data.frame")) 
  </code></pre>