[GRASS-dev] r.univar -e

[Martin Landa]

Hamish,

2006/9/6, Hamish <hamish_nospam at yahoo.com>:

> I have merged your patch locally with a few minor changes:
>   http://bambi.otago.ac.nz/hamish/grass/r.univar_ext.c
>     or if you prefer,
>   http://bambi.otago.ac.nz/hamish/grass/r.univar_ext.diff
>
> A few comments/questions before putting it in CVS:
>
> * It is quite a bit faster than r.univar.sh! (I guess this is to be
> expected, but it's always nice to see)

It should be:-)

> * qsort() comparison functions are declared as static int.
> a) shouldn't they just be int?
> b) could/should these fns be inlined for speed?

Not sure, ...

> * GRASS 5's s.cellstats uses something called qisort() instead of
> qsort(), which claims to be faster. Comments from the crowd?
>  http://freegis.org/cgi-bin/viewcvs.cgi/grass/src/sites/s.cellstats/qisort.c?rev=HEAD&content-type=text/vnd.viewcvs-markup

Hm, I have simply tested

time r.univar elevation.10m -e 2>/dev/null| grep s$

real    0m0.817s
user    0m0.764s
sys     0m0.052s

time r.univar elevation.10m -e 2>/dev/null| grep s$

real    0m0.532s
user    0m0.516s
sys     0m0.016s

Not sure, should be qisort function part of GRASS library?

> * Are there any issues with having shell variables (-g flag) which start
> with a number?
>
> * I've held off on reformatting the output. Your patch assumes that the
> font will be monospaced, while the new GUI(s) may prefer to use a
> proportional font.
>
> * fabsf() removed as it's non-POSIX. fabs() used instead.
>
> * Kept "Mean" instead of "Arithmetic mean". Sample, population,
> geometric means don't apply in this context, so keep it simple.

Agreed

>
>
> TODOs
>  easy: mean of squares  (if anyone needs this just ask & I'll put it in)
>  harder: mode, skewness, kurtosis   (begging required, file a wish)

Nice to know:-)

Best, Martin

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-- 
Martin Landa <landa.martin at gmail.com> * http://gama.fsv.cvut.cz/~landa *