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.
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@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.
__________________________________________________
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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@yahoo.com> wrote:
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@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
>
> _______________________________________________
> grassuser mailing list
> grassuser@grass.itc.it
> http://grass.itc.it/mailman/listinfo/grassuser
>
__________________________________________________
Correo Yahoo!
Espacio para todos tus mensajes, antivirus y antispam ¡gratis!
Regístrate ya - http://correo.espanol.yahoo.com/
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.
v.reclass column= will reset the column which is used for the category
information. The column must be an integer type.