[GRASS-user] How to add a new column based of polyline cat.

[Kenneth Roy Cabrera Torres]

Dr. Kattwinkel:
Thank you for your answer.
When you say about the "db.execute" you mean to make a "join" SQL operation.
You are right.

But at the moment when I generate the polylines with v.build.polyline, I
lose the ID of each segment current.
So I don't know how can I keep the current segment ID and the polyline of
each Horton current to make the join command.

What do you think is the best way to do that?

Best wishes.


El vie, 11 dic 2020 a las 3:38, Mira Kattwinkel (<
kattwinkel-mira at uni-landau.de>) escribió:

> Dear Kenneth
>
> db.execute might be an option to fill a new column with what you want. I
> am not an SQL expert, but I suppose it is possible to concatenate the right
> strings if you do it for each order separately and count the number of
> currents first.
>
> Cheers,
>
> Mira
> On 10/12/2020 17.15, Kenneth Roy Cabrera Torres wrote:
>
> Dear GRASS users:
>
> Can you give any suggestions to solve this problem?
>
> I have an ordered dataset of segments of river currents output from
> r.stream.order command.
> I will like to add a column to this dataset that identifies each current
> according to Horton ordering.
> I mean it actually identifies the Horton number. But what I want to do is
> to separate each
> Horton current from each order. For example, if I have, say 4 Horton
> currents of order 5,
> then I will like to have an additional column that identifies each Horton
> current (5-1, 5-2, ..., 5-4).
>
> I try with v.build.polyline and indeed it separates the individual
> currents of the same
> Horton order. But I don't know how to incorporate that new cat ID to the
> current segments' dataset.
>
> Thank you for your help.
>
> --
> Kenneth Roy Cabrera Torres
> Cel 315 504 9339
>
> _______________________________________________
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>
> --
> Dr. Mira Kattwinkel
> Quantitative Landscape Ecology
> iES Landau, Institute for Environmental Sciences
> University of Koblenz-Landau
> Fortstraße 7
> 76829 Landau
> Germany
> Phone: + 49 6341 280-31553
> Office: Building I, Room 2.02
>
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>


-- 
Kenneth Roy Cabrera Torres
Cel 315 504 9339
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