[GRASS-user] Learning to use vector layers

[Daniel Victoria]

Yea, that could do it also, just have to figure out how to perform
different queries for each column so I'd have average January on  col
1 and avg February on two and so on. Probably a bunch of table
updates?

Thanks
Daniel

On 3/26/07, Jaime Carrera <jaicarrerahdez at yahoo.com> wrote:
> Hi Daniel,
>
> You could also generate a table like this:
>
> id|easting|northing|9001|9002|9003|...|9012|9101|...
>
> Then you have your data in one table which can be
> linked to the vector file. Such a table can be
> generated from other tables using SQL commands.
>
> HTH
>
> Jaime
>
>
> --- Daniel Victoria <daniel.victoria at gmail.com>
> escribió:
>
> > Hi all,
> >
> > I have a vector problem and I think it might be a
> > job for vector layers.
> > I have a postgresql table with daily meteorological
> > station data (~10
> > years, 300 stations) and I'd like to get average
> > monthly precipitation
> > for each station.
> > That I can easily do with a SQL query, generating a
> > view and attaching
> > the view to a vector file where the CAT column is
> > the station number.
> > The problem is, I can only attach one SQL view at a
> > time since the
> > vector file has only one category (from what I read,
> > it's one category
> > per layer connection correct?)
> >
> > So, I though about some options:
> > 1) either generate 1 vector file for each month -
> > simple but then I
> > don't learn about layers
> > 2) keep changing the database connection for each
> > month - works but
> > seems kind of improvisation
> > 3) Use layers, one layer for each month. I'd have
> > the advantage of not
> > having categories for stations with no data for a
> > specific month for
> > example and also, I'd learn about layers
> >
> > So, the proper questions:
> > Does this sounds like a job for vector layers?
> > How do I add categories to a vector file but, the
> > categories should
> > come from a column in a SQL view? From what I read,
> > v.category can
> > only add sequential cats and I'd like the cats to be
> > the station
> > number.
> >
> > Cheers and sorry for the long email
> > Daniel
> >
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>
>
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