[GRASS5] g51 v.build accelerated

[Markus Neteler]

On Mon, Feb 18, 2002 at 08:18:53AM +0100, Andrea Aime wrote:
> Radim Blazek wrote:
> > 
> > v.build accelerated now:
> > 
> > grass50  grass51
> > 270s     9s     (with attributes)
> > 124s     6s     (without attributes)
> > 
> > How boring. Somebody should check, seems to be too good.
> > 

Hi Radim,

as promised I made a test with 5.1 and compared the last week's and the
latest version of v.build (330000 lines SHAPE, 1GHz machine)

"Old" version:

time v.build map=ITAIT2________GC.shp option=build
Registering lines: xxxxx/338971
338971 lines registered
Building areas:  100%
0 areas built
0 isles built
Attaching islands:
Attaching centroids:  100%
Writing topo file ...
Topology was built.
Number of primitives:   338971
Number of points    :   0
Number of lines     :   338971
Number of boundaries:   0
Number of centroids :   0
Number of areas     :   0
Number of isles     :   0
 
real    154m11.405s
user    153m47.620s
sys     0m13.000s

-> 154min -> 9420sec + 11.405sec
--> 2:30h, not really fast.

[recompiled the new version]

"New" version:
time v.build map=ITAIT2________GC.shp option=build
Build topology for 338971 shapes:
Registering lines:
338971 lines registered
Building areas:  100%
0 areas built
0 isles built
Attaching islands:
Attaching centroids:
Writing topo file ...
Topology was built.
Number of nodes     :   283431
Number of primitives:   338971
Number of points    :   0
Number of lines     :   338971
Number of boundaries:   0
Number of centroids :   0
Number of areas     :   0
Number of isles     :   0
 
real    0m22.022s
user    0m10.510s
sys     0m4.000s

Comparing the results:

> 22.022/9251.405
[1] 0.002380395

The new version takes 0.2% (note: below 1 percent) of the time of the 
old version of v.build.

GREAT JOB, Radim!! It is incredible fast now. Next I
will fill in the GSHHS data, another really large vector data set.

Thanks,

 Markus