title: How can I reduce the space between two discrete values in the x-axis?
body: <p>First of all, I would like to do this without ggplot.</p>
  
  <p>I have this script for a boxplot:</p>
  
  <pre><code>data &lt;- data.frame(
    u    = c(0.522, 0.488, 0.474, 0.443, 0.510, 0.443, 0.420, 0.554, 0.333, 0.414,
             0.467, 0.606, 0.588),
    ub   = c(0.594, 0.568, 0.578, 0.523, 0.577, 0.501, 0.522, 0.623, 0.498, 0.511,
             0.544, 0.654, 0.639),
    nu   = c(0.646, 0.620, 0.644, 0.607, 0.667, 0.614, 0.631, 0.701, 0.586, 0.589,
             0.664, 0.739, 0.744),
    nub  = c(0.733, 0.701, 0.700, 0.698, 0.724, 0.701, 0.722, 0.777, 0.630, 0.663,
             0.703, 0.78, 0.787),
    wnub = c(0.815, 0.782, 0.757, 0.764, 0.792, 0.771, 0.838, 0.860, 0.700, 0.703,
             0.774, 0.837, 0.863))
  boxplot(data, las=1, par(mar=c(7.5, 4.2, 0.25, 0.15)), axes=FALSE, xlab=NA,
          ylab=NA, boxwex=.4, outline=FALSE, ylim=c(0:1))
  box()
  labnames = c("Unigrams",
               "Unigrams\n&amp; Bigrams",
               "Noun Unigrams",
               "Noun Unigrams\n&amp; Noun Bigrams",
               "Noun Unigrams\n&amp; Noun Bigrams\n(positional weights)")
  axis(side=1, tck=-0.025, labels=FALSE)
  axis(side=1, lwd=0, labels=FALSE, at=c(1:5), cex.axis=1)
  text(seq(1, 5, by=1), par("usr")[3]-.2, labels=labnames, srt=-90,
       xpd=TRUE, adj=.25)
  axis(side=2, tck=-0.02, labels=NA)
  axis(side=2, lwd=0, cex.axis=1, las=1)
  mtext(side=1, "Feature Sets", line=6.5, cex=1.5)
  mtext(side=2, "F-Score", line=3, cex=1.5)
  </code></pre>
  
  <p>which produces the following figure:</p>
  
  <p><img src="https://i.stack.imgur.com/aC5cS.png" alt="boxplot"></p>
  
  <p>I am annoyed by the amount of whitespace this is wasting. One way I've been trying to reduce the space is by bringing the discrete x-axis values closer together by using "asp", but it doesn't change anything. How can I do this so that the huge gap between the boxes are reduced?</p>
  
  <p>Also, if there any other ways to reduce the whitespace in this picture, please share your thoughts.</p>