Efficient conversion from string to number

Question

Is there a way to convert a list of string to numbers faster than ToExpression?

str = ToString /@ RandomReal[100, 1000];
ToExpression@str; // AbsoluteTiming // First
(* 0.007714 *)

Related: How to convert string to integer list?

Edit Thanks to J.M. who pointed to this answer:

  Internal`StringToDouble/@str; // AbsoluteTiming // First
 (* 0.000834 *)

Have you seen this? – J. M.'s missing motivation Mar 07 '18 at 21:50 — J. M.'s missing motivation, Mar 07 '18 at 21:50
@J.M. Wow, no I had not! Probably hard to beat... – anderstood Mar 07 '18 at 21:55 — anderstood, Mar 07 '18 at 21:55

score 6 · Answer 1 · answered Jun 10 '18 at 02:05

6

I'd just like to point out the J.M.'s answer is also best if you have ints, since Floor is fast and listable as a cast from Real:

intStrings = RandomInteger[10000, 100000] // Map[ToString];

Floor[Internal`StringToDouble /@ intStrings] // RepeatedTiming // First

0.048

ToExpression@intStrings // RepeatedTiming // First

0.413

answered Jun 10 '18 at 02:05

b3m2a1

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Maybe you can incorporate J.M.'s answer too (as community if you're not comfortable) so that I can accept it. – anderstood Jun 11 '18 at 00:39

Efficient conversion from string to number

1 Answers1