Problem solved! Suggestion was made to use db.execute and it worked without variable declaration. Thanks for your insight! On Aug 30, 2016 3:17 AM, "Moritz Lennert" <[email protected]> wrote:
> Dear Alassane, > > Please keep conversations on the list. > > On 29/08/16 19:49, alassane toure wrote: > >> Dear Moritz, >> I am a newbi in python programming. Following your instructions i added >> the followings.. >> >> par_sqf=[] >> c_number=[] >> pchng=[] >> >> but pchng stayed NULL for all rows (see below)! >> > > You set pchng = range(len(par_sqf)), > but par_sqf is only defined as a Python variable by > > par_sqf=[] > > so it is normal that it is NULL. > > Don't mix up Python variables and vector map column names. > > If you want to set the attribute column pchng to contain a value that is > equal to the length of the value of the attribute column par_sqf (i.e. > count the number of digits (plus decimal point) in the area value), then > you have to use v.db.update: > > v.db.update map=parcel column=pchng qcol="length(par_sqf)" > > Although I don't understand what the sens of such a length would be. > > Maybe it would be easier if you explained us what you are trying to do, > instead of only how you are doing it. > > Moritz >
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