I have two lists which I generated from two plots.

list1 = Cases[
Cases[InputForm[plot1], Line[___], 
Infinity], {_?NumericQ, _?NumericQ}, Infinity];

list2 = Cases[
Cases[InputForm[plot2], Line[___], 
Infinity], {_?NumericQ, _?NumericQ}, Infinity];

Now I want to divide the list1 by list2 and then plot this resulting list3 vs. x. Can anyone please help me with this?

  • $\begingroup$ Please format the post an place all code in a code block. Make sure that the code can be copied back into Mathematica intact. Click edit above, then if you need help click the ? button in the editing toolbar. $\endgroup$
    – Szabolcs
    Sep 5, 2016 at 8:39
  • $\begingroup$ If the lists are of equal length, then the division operator / works as expected. $\endgroup$
    – Feyre
    Sep 5, 2016 at 8:43
  • $\begingroup$ Just a comment: list division only makes sense if both lists are on the same x-grid. $\endgroup$ Sep 5, 2016 at 10:57
  • $\begingroup$ Yes, they are on the same grid. $\endgroup$
    – cosmos
    Sep 5, 2016 at 11:48

1 Answer 1


The problem here is that list1 and list2 will not be on the same gridding (i.e. at the same x positions}. So the general approach is to convert the lists into interpolation functions and divide the two.

plot1 = Plot[Sin[x], {x, 0, 10}];
plot2 = Plot[x, {x, 0, 10}];
list1 = Cases[
   Cases[InputForm[plot1], Line[_], 
   Infinity], {_?NumericQ, _?NumericQ}, Infinity]; 
list2 = Cases[ 
   Cases[InputForm[plot2], Line[_], 
   Infinity], {_?NumericQ, _?NumericQ}, Infinity];

Unequal lengths:

Length[list1] == Length[list2]
<* Out[] = False *>

inter1 = Interpolation[list1];
inter2 = Interpolation[list2];
Plot[inter1[x]/inter2[x], {x, 0, 10}]

enter image description here

  • $\begingroup$ Thanks a lot Markus! Interpolation solved my problem! The problem was that the lists were not of same size and that's why simple divide function "/" was not working. $\endgroup$
    – cosmos
    Sep 5, 2016 at 10:23

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