[GRASS-user] re-order boundaries by relative position along polyline
Thomas Adams
tea3rd at gmail.com
Tue Apr 7 08:54:55 PDT 2015
Adrien,
Thank you! I'll give it a try...
Tom
On Tue, Apr 7, 2015 at 10:44 AM, Adrien André <adrien.andre at onf.fr> wrote:
> Dylan, Tom,
>
> not about the main question, but to complete Tom's answer:
>
> I had once to vectorize a raster stream network according to flow
> direction.
> You can find here the Python script i wrote:
> https://github.com/adrienandrem/r.to.vect.dir
>
> I hope this helps.
>
>
> Regards,
>
> Adrien
>
>
> Le 05/04/2015 14:48, Thomas Adams a écrit :
> > Hi Dylan!
> >
> > (I'm about to start a new position — more on that later). This may help…
> >
> > I had a problem somewhat analogous to this a little while ago, where I
> > needed to create a text file that, among a couple of other things,
> > needed to identify the 'downstream' pixel for all grid cells within a
> > basin area. I was able to do that with help here, but an issue I had was
> > that the integer IDs needed to be numbered from 0-N in basically
> > upstream to downstream order, but after my GRASS analysis I had IDs with
> > some large number ranging to some other very large number for the IDs
> > and the 'downstream IDs' (with values skipped and not in order). I got
> > help writing a Perl script that uses hashes for a lookup table to relate
> > the old ID to the new ID.
> >
> > Perhaps you could do something like this, starting with a new vector map
> > (copy) where you could simply update the attributes using an SQL query?
> > Some coding would be needed, obviously…
> >
> > Just my 2 cents…
> >
> > Cheers!
> > Tom
> >
> > On Thu, Apr 2, 2015 at 6:31 PM, Dylan Beaudette
> > <dylan.beaudette at gmail.com <mailto:dylan.beaudette at gmail.com>> wrote:
> >
> > Hi,
> >
> > Once again, I am reminded that complex spatial analysis in other
> > software
> > can usually be reduced to a couple of lines of code in GRASS--
> thanks!
> >
> > Here is a fun question. Suppose you have a set of line segments, or
> > boundaries that are the result of a digitizing process that generated
> > segments out of "order":
> >
> > 2 4 1 3
> > O---------+-----------------+------------+------O
> >
> > 'O' = start / end point
> > '+' = vertex
> >
> > ... in this case "order" is associated with order in which records
> > appear
> > in the attribute table and the order in which segments are drawn on
> the
> > screen.
> >
> > Is there a module, or set of modules that could be used to re-order
> the
> > segments so that the order of records in the attribute table and
> drawing
> > order is:
> >
> > 1 2 3 4
> > O---------+-----------------+------------+------O
> >
> > Note that I do not wan't to shuffle the linkages between geometry and
> > attributes, rather, I would like to re-order the segments and
> attribute
> > table according to the linear position within the set of contiguous
> > boundaries or polyline.
> >
> > Here is an example set of lines in ASCII format, WGS84 GCS.
> >
> > ORGANIZATION:
> > DIGIT DATE:
> > DIGIT NAME: dylan
> > MAP NAME:
> > MAP DATE: Thu Apr 2 11:46:34 2015
> > MAP SCALE: 1
> > OTHER INFO:
> > ZONE: 0
> > MAP THRESH: 0.000000
> > VERTI:
> > B 6 1
> > -118.71960108 36.71846736
> > -118.71946261 36.71783146
> > -118.71905508 36.71717314
> > -118.71863837 36.71610377
> > -118.71807413 36.71546352
> > -118.71786286 36.71527706
> > 2 132
> > B 3 1
> > -118.7153795 36.73403608
> > -118.71537992 36.73272737
> > -118.71538933 36.73177277
> > 2 133
> > B 3 1
> > -118.71536851 36.76205202
> > -118.7153724 36.7609144
> > -118.71537619 36.75980591
> > 2 150
> > B 2 1
> > -118.73128842 36.69749903
> > -118.73130166 36.69760244
> > 2 175
> > B 5 1
> > -118.71538933 36.73177277
> > -118.7153944 36.73125742
> > -118.71573607 36.73044156
> > -118.71618977 36.72875872
> > -118.71651025 36.72811846
> > 2 581
> > B 15 1
> > -118.71651025 36.72811846
> > -118.71661716 36.72766138
> > -118.71660977 36.7273294
> > -118.71645785 36.72668322
> > -118.71689758 36.7261392
> > -118.71724087 36.72567564
> > -118.71747107 36.7248177
> > -118.71753527 36.72390024
> > -118.71787045 36.72307308
> > -118.71797278 36.72237579
> > -118.71781832 36.72073331
> > -118.71825483 36.72004703
> > -118.71908689 36.71948153
> > -118.71963768 36.71863545
> > -118.71960108 36.71846736
> > 2 602
> > B 8 1
> > -118.7180943 36.70872005
> > -118.71827421 36.7083356
> > -118.71841915 36.7080259
> > -118.7190169 36.70752707
> > -118.72008403 36.70694237
> > -118.72042476 36.70636815
> > -118.72049695 36.70608245
> > -118.7212077 36.70547966
> > 2 604
> > B 15 1
> > -118.7212077 36.70547966
> > -118.721692 36.70506892
> > -118.72256889 36.70442599
> > -118.72372477 36.702873
> > -118.72417965 36.70213899
> > -118.72496002 36.70190631
> > -118.72660809 36.70183505
> > -118.72765407 36.70118732
> > -118.72831767 36.70100376
> > -118.72866574 36.7007615
> > -118.72887421 36.70026501
> > -118.72998965 36.69849669
> > -118.73066541 36.69798083
> > -118.73118943 36.69770441
> > -118.73130166 36.69760244
> > 2 609
> > B 8 1
> > -118.7153867 36.75138736
> > -118.7153804 36.7500365
> > -118.7153634 36.7464107
> > -118.7153465 36.742785
> > -118.7153296 36.7391593
> > -118.71533791 36.73753527
> > -118.7153438 36.7363838
> > -118.7153795 36.73403608
> > 2 610
> > B 13 1
> > -118.71786286 36.71527706
> > -118.71763335 36.71507451
> > -118.71748992 36.71480774
> > -118.71754381 36.71369999
> > -118.71750723 36.7131568
> > -118.71786592 36.71228789
> > -118.71745106 36.71129755
> > -118.71716489 36.71079564
> > -118.71709787 36.71043286
> > -118.71712906 36.71006868
> > -118.71740871 36.70978478
> > -118.717644 36.709369
> > -118.7180943 36.70872005
> > 2 612
> > B 7 1
> > -118.71411256 36.77582538
> > -118.71445897 36.77550631
> > -118.71478471 36.77508229
> > -118.7149828 36.77446623
> > -118.71532537 36.77406797
> > -118.7153339 36.7717931
> > -118.71534777 36.76808916
> > 2 613
> > B 3 1
> > -118.71534777 36.76808916
> > -118.71536 36.7645405
> > -118.71536851 36.76205202
> > 2 622
> > B 4 1
> > -118.71537619 36.75980591
> > -118.7153848 36.7572883
> > -118.7153973 36.7536622
> > -118.7153867 36.75138736
> > 2 623
> >
> >
> > I have been able to convert these segments into polylines, however,
> I am
> > not sure how one would go about computing the position along the
> > polylines.
> > Perhaps a linear referencing system?
> >
> >
> >
> > Thanks!
> > Dylan
> > _______________________________________________
> > grass-user mailing list
> > grass-user at lists.osgeo.org <mailto:grass-user at lists.osgeo.org>
> > http://lists.osgeo.org/mailman/listinfo/grass-user
> >
> >
> >
> >
> > --
> > Thomas E Adams, III
> > 718 McBurney Drive
> > Lebanon, OH 45036
> >
> > 1 (513) 739-9512 (cell)
> >
> >
> >
> > _______________________________________________
> > grass-user mailing list
> > grass-user at lists.osgeo.org
> > http://lists.osgeo.org/mailman/listinfo/grass-user
> >
>
> _______________________________________________
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>
--
Thomas E Adams, III
718 McBurney Drive
Lebanon, OH 45036
1 (513) 739-9512 (cell)
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