title: Gnuplot: Trouble creating heat map / reading data
body: <p>(I hope you get the meaning of what I write, english isn't my mother tongue.)</p>
  
  <p>I have trouble creating a heat map showing air humidity using a txt file. 
  My data looks like this:</p>
  
  <pre><code>26.02.13 10:30:00 MEZ   31.79688    31.0625 32.875  31.8125 31.46875    30.9375 39.0    36.71875    36.1875
  26.02.13 10:45:00 MEZ   31.875  31.10938    32.75   31.8125 31.46875    30.9375 39.0    36.71875    36.1875
  26.02.13 11:00:00 MEZ   31.82813    31.15625    32.84375    31.8125 31.48438    30.9375 39.0    36.71875    36.1875
  ...
  </code></pre>
  
  <p>Its not a matrix, it's: </p>
  
  <p>date1, time1, timezone, value1-room1, value1-room2, value1-room3,...</p>
  
  <p>date2, time2, timezone, value2-room1, value2-room2, value2-room3,...  </p>
  
  <p>I inserted a blank line each 96 values to "seperate" the days from each other</p>
  
  <p>this is what my code, so far, looks like(i left out labels etc.):</p>
  
  <pre><code>reset
  set cbrange [0:100]
  set palette defined (0 '#0000BB',0.091 '#0055FF',0.182 '#44BBEE',0.2728 '#DDFFDD',0.273 '#DDFFBB',0.45 '#DDFF44',0.5 '#FFFF00',0.55 '#FFF600',0.61 '#FFEE00',0.66 '#FFDD00',0.727 '#FFBD00',0.7272 '#FFBB00',0.86 '#FA2200',0.92 '#EA0000',1.0 '#880000')
  set cblabel "Humidity"
  set cbtics 0,20,100
  
  set timefmt '"%d.%m.%y %H:%M:%S"' 
  
  set format x '"%d.%m.%y"'
  set xrange ['"26.02.13"':'"27.03.13"']
  
  set format y '"%H:%M:%S"'
  set xrange ['"00:00:00"':'"23:59:59"']
  
  plot "data.txt" using 1:2:4
  </code></pre>
  
  <p>My intention was to create a heat map for room 1. If that works I want to create heat maps for the other rooms, but first things first :-) </p>
  
  <p>**the problems i can't solve are:</p>
  
  <p>"Skipping unreadable file "data.txt""</p>
  
  <p>and</p>
  
  <p>"Can't plot with an empty x range"**</p>
  
  <p>why is my file unreadable? its in ANSI, the blank lines should tell gnuplot where to start over again</p>
  
  <p>why is the x range empty? did i specify it wrong?</p>
  
  <p>all files are located in the "bin" directory of gnuplot, the "data.txt" has a length of ca. 2000 lines, my gnuplot version is 4.6 </p>
  
  <p>thanks in advance</p>
  
  <p>Johannes</p>