title: Performing math operations on loaded data with GNUplot
body: <p>I'm using Linux with gnuplot and looking to load a simple two-column data file and plot/save it from a some python code.</p>
  
  <p>I've had no issues following the tutorials and examples with the exception that now I want to perform a mathematical operation on one of the columns, e.g. take the <code>log10()</code> of the column so that I'm plotting (for example) <code>(x, log10(y))</code> where <code>x</code> and <code>y</code> are the two columns in the data file.</p>
  
  <p>This is the perfect link showing how to do it:</p>
  
  <p><a href="https://stackoverflow.com/questions/6938703/how-to-plot-a-function-of-an-imported-data-in-gnuplot">How to plot a function of an imported data in gnuplot?</a></p>
  
  <p>The problem is that I want to run a bash script of gnuplot using <code>gnuplot -e ......</code>, since I'm running it from Python, and it immediately removes the <code>$</code> signs from my script and it doesn't work. If I choose not to transform the data (leave it as is) it runs fine, so all other syntax is okay.</p>
  
  <p>Truth be told, I don't know what the <code>$</code> sign is trying to convey and I'm thinking it has something to do with my operating system or something else and not strictly gnuplot. Any insight here would be great.</p>