title: Barplot with continuous x axis using base r graphics
body: <p>I am looking to scale the x axis on my barplot to time, so as to accurately represent when measurements were taken.</p>
  
  <p>I have these data frames:</p>
  
  <pre><code>    &gt; Botcv
          Date Average       SE
  1 2014-09-01     4.0 1.711307
  2 2014-10-02     5.5 1.500000
  
  &gt; Botc1
          Date Average        SE
  1 2014-10-15   2.125 0.7180703
  2 2014-11-12   1.000 0.4629100
  3 2014-12-11   0.500 0.2672612
  
  &gt; Botc2
          Date Average        SE
  1 2014-10-15   3.375 1.3354708
  2 2014-11-12   1.750 0.4531635
  3 2014-12-11   0.625 0.1829813
  </code></pre>
  
  <p>I use this code to produce a grouped barplot:</p>
  
  <pre><code>covaverage &lt;- c(Botcv$Average,NA,NA,NA)
  c1average &lt;- c(NA,NA, Botc1$Average)
  c2average &lt;- c(NA,NA, Botc2$Average)
  date &lt;- c(Botcv$Date, Botc1$Date)
  
  averagematrix &lt;- matrix(c(covaverage,c1average, c2average), nrow=3, ncol=5, byrow=TRUE)
  
  barplot(averagematrix,date, xlab="Date", ylab="Average", axis.lty=1, space=NULL,width=3,beside=T, ylim=c(0.00,6.00))
  </code></pre>
  
  <p>R plots the bars equal distances apart by default and I have been trying to find a workaround for this. I have seen several other solutions that utilise ggplot2 but I am producing plots for my masters thesis and would like to keep the appearance of my barplots in line with other graphs that I have created using base R graphics. I also want to add error bars to the plot. If anyone could provide a solution then I would be very grateful!! Thanks!</p>