title: How to plot a response variable with 3 factors in R?
body: <p>I have the following table in R:</p>
  
  <pre><code>  ExperimentID clients connections msgSize     Mean Deviation     Error
  1             4      50          50      10 73.19379 21.313889 0.2263254
  2             5      50          10      10 73.25170 21.457139 0.2265276
  3             6      50         100      10 73.20642 21.396485 0.2261432
  4             7      50          50    1999 53.75247 11.863616 0.1695395
  5             8      50          10    1999 53.88464 12.778998 0.2234775
  6             9      50         100    1999 53.99422 11.947930 0.2085102
  7            10      10          50    1999 49.74034  9.296995 0.3855425
  8            11      10          10    1999 49.77624  8.639379 0.3566724
  9            12      10         100    1999 50.30912 10.800443 0.4442306
  10           13      10          50      10 68.80108 19.674006 0.5892552
  11           14      10          10      10 69.41143 19.671618 0.5845524
  12           15      10         100      10 69.09130 19.821473 0.5894541
  13           16     100          10    1999 56.32045 16.370877 0.1940681
  14           17     100          50    1999 55.93405 14.007772 0.2272496
  </code></pre>
  
  <p>Now, I want to plot the column "Mean" as a function of the factors: clients, connections and
  msgSize. I think that a reasonable way to do this would be to prepare two histograms, one for msgSize = 10, and another for msgSize = 1999. In each of these two histograms, I can have the number of clients on the x-axis and the mean on y-axis. For each tick on the x-axis (ie. for a particular value of clients), I can have 3 bars (each corresponding to the mean for 10, 50 or 100 connections). How can I achieve this in R? </p>
  
  <p>P.S: I am a newbie to R, so a bit detailed answer would be helpful. If there is a better answer with ggplot, that is also fine.</p>