I generated 2 .dat files with 1000 data points separately, imported as Table and flatten them, then combined and formed a Table for ListPlot. But it gives me a blank plot and I don't know why.

Here's the full code:

a = OpenWrite["a0_sim.dat"];
p = OpenWrite["p_sim.dat"];

bmax[\[Theta]w_] := (1.14*10^9)/Sin[\[Theta]w/2]^(9/7);
db[\[Theta]w_] := bmax[\[Theta]w]/10^5;
Pb[\[Theta]w_, b_] := (2 b db[\[Theta]w])/bmax[\[Theta]w]^2;        
a0[\[Theta]w_, b_] := (9*10^10)/((2.5*10^63)/(Sin[\[Theta]w/2]^7 b^7)-Sin[\[Theta]w/2]^2); 

n = 10^3;
m = 0;
While[m < n, {\[Theta]w = \[Pi] Random[];
               b = bmax[\[Theta]w] Random[];
               Write[a, a0[\[Theta]w, b]];
               Write[p, Pb[\[Theta]w, b]];
ain = Flatten@Import["a0_sim.dat"];
pin = Flatten@Import["p_sim.dat"];
ap = Table[{ain[[i]], pin[[i]]}, {i, 1, Length@ain}];

And what my table prints like: enter image description here

This is really troubling me and thanks so much for your help!

  • 2
    $\begingroup$ Please show the ListPlot command you used. Display all code and data in Mathematica format, not as images. $\endgroup$
    – bbgodfrey
    Jul 26, 2017 at 3:26

1 Answer 1


Here's the Mathematica way of achieving that:

bmax[θw_] := (1.14*10^9)/Sin[θw/2]^(9/7);   
db[θw_] := bmax[θw]/10^5;
Pb[θw_, b_] := (2 b db[θw])/bmax[θw]^2;
a0[θw_, b_] := (9*10^10)/((2.5*10^63)/(Sin[θw/2]^7 b^7)-Sin[θw/2]^2);
ap = Table[
   θw = π Random[];
   b = bmax[θw] Random[];
   {a0[θw, b], Pb[θw, b]}
   , {m, 0, 10^3}];

enter image description here

If in addition you want to export the files, use Export.

  • $\begingroup$ Thanks so much! That does the job so tidy. So does my problem occurs because my coding complicates things? But where is the problem exactly, if I may ask? $\endgroup$ Jul 26, 2017 at 4:05
  • $\begingroup$ I didn't bother to look for the mistake. The advantage of doing things in the "natural" way is that things are "automatically" fine and you avoid having to solve problems that simply don't occur in the first place. I'd recommend going over this post to get some basic Mathematica practices. $\endgroup$
    – yohbs
    Jul 26, 2017 at 13:11

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