Hi list,
I've been looking around trying to solve this problem; unfortunately I
haven't found a way to solve it.
I have a database with sampling points with an associated sampling date
and would like to plot the density of sampling points on a monthly basis
for one year using spplot. However, I need to query the database and
import the result of the query into R to visualize the data. I can
import the query on a column-wise basis but the WKB data are imported as
chars into R (as expected). Is there a way by which I could read these
data (WKB geometry) once imported into R? Or is there a way by which
ReadOGR can read the outcome of the query?
I tried creating a temporary table through the query, but it seems that
ReadOGR can't read it.
Thanks for your help,
Jaime
As an example:
> db.execute("select geo.id as id,geo.wkb_geometry as geom from wells
as geo, gwhead as h where geo.id=h.id and date_part('year',h.date)=2001
and h.gwhead<700",clear=F)
> ids<-db.read.column("id",as.is=F)
> geom<-db.read.column("geom",as.is=F)
Warning message:
In rpgsql.cast.values.default(data.col) :
Coercing PGSQL type 16437 to character
> geom
[1] "0101000020FF7F00000000000088FD2141000000C09BB95741"
[2] "0101000020FF7F00000000000088FD2141000000C09BB95741"
[3] "0101000020FF7F00000000000088FD2141000000C09BB95741"
[4] "0101000020FF7F00000000000088FD2141000000C09BB95741"
[5] "0101000020FF7F00000000000088FD2141000000C09BB95741"
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