On Feb 8, 2008 10:31 AM, Francesc Altet <faltet@carabos.com> wrote:
A Friday 08 February 2008, Francesc Altet escrigué:
A Friday 08 February 2008, Charles R Harris escrigué:
Also, in the context of my work in indexing, and because of the slowness of the current implementation in NumPy, I've ended with an implementation of the quicksort method for 1-D array strings. For moderately large arrays, it is about 2.5x-3x faster than the (supposedly) mergesort version in NumPy, not only due to the quicksort, but also because I've implemented a couple of macros for efficient string swapping and copy. If this is of interest for NumPy developers, tell me and I will provide the code.
I have some code for this too and was going to merge it. Send yours along and I'll get to it this weekend.
Ok, great. I'm attaching it. Tell me if you need some clarification on the code.
Ops. I've introduced a last-minute problem in my code. To fix this, just replace the flawed opt_strncmp() that I sent before by:
static int inline opt_strncmp(char *a, char *b, int n) { int i; for (i=0; i<n; i++) { if (a[i] > b[i]) return i+1; if (a[i] < b[i]) return -(i+1); /* Another way, but seems equivalent in speed, at least here */ /* if (a[i] != b[i]) */ /* return (((unsigned char *)a)[i] - ((unsigned char *)b)[i]); */ } return 0; }
Apparently, this version works just fine.
Did you find this significantly faster than strncmp? There is also a unicode compare, do you have thoughts about that? Chuck