[GRASS-user] Python-Loop over points
Johannes Radinger
JRadinger at gmx.at
Wed Apr 6 06:48:52 EDT 2011
Hello,
I want to reactive this thread...
and want just to put in some new ideas...and i still want to use a for-loop
or something similar on a point-vector-file in a Python-script
i want something like Daniel mentioned but want to loop over points within one single pointfile:
for point in "points_file": --> that is the line I don't know, I want to get point per point and it's ID
grass.run_command("r.streams.basins", dir = "flow_direction, points=point_ID, basins = out_map_ID)
@Stephen sefick: do you have solved that issue already?
I think that is a quite common problem, therefore I think there must be a quite simple solution....
is a point-file a loopable element? how would an example look like?
I am looking for a similar approach what ArcGIS is using now in their new modeller (Iterator).
/johannes
Am 22.02.2011 um 15:57 schrieb stephen sefick:
> Why not create a temporary vector map from the larger vector map in
> the for loop; do what needs to me done; clean up.
>
> I would be interested in you solution, and could offer some help if
> you would like. I am going to have to process similar data.
> HTH
>
> Stephen
>
> On Tue, Feb 22, 2011 at 1:35 AM, Johannes Radinger <JRadinger at gmx.at> wrote:
>>
>> Am 22.02.2011 um 02:07 schrieb Daniel Victoria:
>>
>>> I'm not sure but from what I read in the r.stream.basins description,
>>> you can have more than one point in your vector file in roder to
>>> delineate your basins. Now, in case you have one basin inside another,
>>> what I did once was:
>>> 1) get x,y coordinates of each point using v.out.ascii
>>> 2) for each point run r.watershed...
>> Yes, thats what I want as well, but I want to automatize it and not to run for each
>> point manually. I also want to run
>> for each point a grass-function (not necessarily r.stream etc.)
>> I just want to know how it basically works to loop over points.
>>
>> to things I thought:
>> 1) loop over the ascii if that is possible
>> 2) use the for loop in combination with v.db.select, but I don't know how that
>> will work in python
>>
>> /johannes
>>
>>
>>>
>>> Cheers
>>> daniel
>>>
>>> On Fri, Feb 18, 2011 at 11:49 AM, Johannes Radinger <JRadinger at gmx.at> wrote:
>>>> Hello,
>>>>
>>>>
>>>> -------- Original-Nachricht --------
>>>>> Datum: Mon, 7 Feb 2011 22:25:31 -0200
>>>>> Von: Daniel Victoria <daniel.victoria at gmail.com>
>>>>> An: Johannes Radinger <JRadinger at gmx.at>
>>>>> CC: grass-user at lists.osgeo.org
>>>>> Betreff: Re: [GRASS-user] Python-Loop over points
>>>>
>>>>> Hi Johannes,
>>>>>
>>>>> You will need to use for loop. Something like this (UNTESTED!)
>>>>>
>>>>> for p in range(5):
>>>>> points_map = "point"+str(p)
>>>>> out_map = "output"+str(p)
>>>>> grass.run_command("r.streams.basins", dir = "flow_direction,
>>>>> points=points_map, basins = out_map)
>>>>>
>>>>> That should work, or at least something similar
>>>>>
>>>>> Daniel
>>>>
>>>> Thank you for your suggestions Daniel, I also thought about
>>>> a for loop. But in your case the loop is using for each iteration
>>>> a input-pointmap called "point"+str(p).
>>>>
>>>> The difference in my
>>>> case is that I've got only one vector map but with several points
>>>> in it and I want to iterate over the single points.
>>>> How is it possible to iterate over the single points? The points are
>>>> stored in a kind of list format, so it should somehow be possible to
>>>> loop over this file, but how?
>>>>
>>>> any suggestions?
>>>>
>>>> /johannes
>>>>
>>>>>
>>>>> On Wed, Feb 2, 2011 at 9:39 AM, Johannes Radinger <JRadinger at gmx.at>
>>>>> wrote:
>>>>>> Hello,
>>>>>>
>>>>>> I am performing e.g. the r.stream.basins calcutlation in python:
>>>>>>
>>>>>> grass.run_command("r.stream.basins",
>>>>>> dir = "flow_direction",
>>>>>> points = "point1",
>>>>>> basins = "output")
>>>>>>
>>>>>> that's working perfectly in the case of one single point in "point1".
>>>>>> How can I do that multiple times when the point layer consist of e.g. 5
>>>>>> points and I want to create an output for each point (create 5 output
>>>>> rasters).
>>>>>>
>>>>>> How can that be done in a python script?
>>>>>>
>>>>>>
>>>>>> thank you
>>>>>>
>>>>>> Johannes
>>>>>>
>>>>>> --
>>>>>> NEU: FreePhone - kostenlos mobil telefonieren und surfen!
>>>>>> Jetzt informieren: http://www.gmx.net/de/go/freephone
>>>>>> _______________________________________________
>>>>>> grass-user mailing list
>>>>>> grass-user at lists.osgeo.org
>>>>>> http://lists.osgeo.org/mailman/listinfo/grass-user
>>>>>>
>>>>
>>>> --
>>>> NEU: FreePhone - kostenlos mobil telefonieren und surfen!
>>>> Jetzt informieren: http://www.gmx.net/de/go/freephone
>>>>
>>
>> _______________________________________________
>> grass-user mailing list
>> grass-user at lists.osgeo.org
>> http://lists.osgeo.org/mailman/listinfo/grass-user
>>
>
>
>
> --
> Stephen Sefick
> ____________________________________
> | Auburn University |
> | Biological Sciences |
> | 331 Funchess Hall |
> | Auburn, Alabama |
> | 36849 |
> |___________________________________|
> | sas0025 at auburn.edu |
> | http://www.auburn.edu/~sas0025 |
> |___________________________________|
>
> Let's not spend our time and resources thinking about things that are
> so little or so large that all they really do for us is puff us up and
> make us feel like gods. We are mammals, and have not exhausted the
> annoying little problems of being mammals.
>
> -K. Mullis
>
> "A big computer, a complex algorithm and a long time does not equal science."
>
> -Robert Gentleman
More information about the grass-user
mailing list