title: Distinct bars of different group in Gnuplot for printing
body: <p>The problem for me is how plot (using gnuplot) bars with different styles in a figure so that they can be print. </p>
  
  <p>Take data from <a href="http://www.ibm.com/developerworks/aix/library/au-gnuplot/" rel="nofollow noreferrer">http://www.ibm.com/developerworks/aix/library/au-gnuplot/</a> for example, the data is: </p>
  
  <pre><code>#Disk.txt
  hdisk2 420 425 410
  hdisk3 700 780 760
  hdisk4 450 450 452
  hdisk5 680 702 690
  hdisk6 320 330 329
  hdisk7 530 515 514
  
      #Gnuplot 
  
  set terminal png truecolor
  set output "diskimage.png"
  set style data histograms
  set style fill solid 1.00 border -1
  plot "disk.txt"  using 2:xtic(1) title "Oct-09 data growth(gb)", '' using 3 title "N
  ov-09 data growth(gb)", '' using 4 title "Dec-09 data growth(gb)"
  </code></pre>
  
  <p>The gnuplot script works and bars are labelled with different colours for distinction of three groups. However, once it is print on the paper, the colours are lost and it is hard to distinct bars anymore. </p>
  
  <p>My question is whether the bars can be plot with different style for different groups. E.g., Fill bars for different group with different filled style? <img src="https://i.stack.imgur.com/sm85H.png" alt="enter image description here"> </p>