How to use Sow and Reap instead of AppendTo for faster computations?

Question

In this example I used appendTo.

f[x_] := x + 1;
data = {};
For[x = 1, x <= 10, x++,
f[x];
spec = AppendTo[data, {x, f[x]}]] // Timing // First

Out[37]= 0.000054

ListPlot[spec]

Does this help you? https://mathematica.stackexchange.com/questions/181597/understanding-sow-and-reap-documentation/181603#181603 — Sjoerd Smit, May 07 '20 at 07:46

score 4 · Answer 1 · answered May 07 '20 at 07:50

4

Try

Reap[For[x = 1, x <= 10, x++, f[x];
Sow[{x, f[x]}]
]][[2, 1]] // AbsoluteTiming
(*0.0000701*)

but it seems to be slower than your vewrsion. Use Table for a significant faster version:

Table[{x, f[x]}, {x, 1, 10}]; // AbsoluteTiming
(*{0.0000199, Null}*)

answered May 07 '20 at 07:50

Ulrich Neumann

3

Rule #1 about learning Mathematica: forget about For. It just doesn't exist. – Sjoerd Smit May 07 '20 at 13:52

1 Answers1