On Thu, Feb 14, 2019, 19:25 Daniel Victoria <[email protected] wrote:
> Never tried it but you got me curious. > > It looks simpler to define a new function or the database using python > sqlite3 libs > > > https://docs.python.org/2/library/sqlite3.html#sqlite3.Connection.create_function > > Cheers > Thanks for the suggestion, this seems still kind of complex to do without proper programming knowledge, I'll try Markus' suggestion on monday, it seems like a much nicer approach than trying to explain numpy in the python console to students. On Thu, Feb 14, 2019 at 12:50 PM César Augusto Ramírez Franco < > [email protected]> wrote: > >> Greetings, >> >> I have a municipality polygon layer with a poverty index (percent) and a >> population count, I'm multiplying them to visualize the vulnerability for >> each municipality, due to the distribution of that new variable I want to >> compute the logarithm, which is not possible in sqlite, so I tried reading >> the column with numpy and issuing a np.log10(). I'm happy with the result, >> but how can I get this new numpy array to a new column in the vector map in >> a simple way? >> >> This is what I already have: >> >> #!/usr/bin/env python >> >> import grass.script as gs >> import numpy as np >> import matplotlib.pyplot as plt >> >> nbi_pob = np.array(gs.vector_db_select("muniant", columns = >> "nbi_pob")["values"].values()).astype(float).squeeze() >> >> plt.hist(nbi_pob) >> plt.show() >> >> log_nbi_pob = np.log10(nbi_pob) >> >> plt.hist(log_nbi_pob) >> plt.show() >> >> I'm trying to introduce this kind of analysis to students who are not >> familiar nor proficient with programming (this is an GIS introductory >> course) so the numpy bit is already complex enough to them, and I'd like to >> avoid using for loops with cursors to achieve this. >> >> Is there a simple solution to this? >> >> -- >> *César Augusto Ramírez Franco* >> _______________________________________________ >> grass-user mailing list >> [email protected] >> https://lists.osgeo.org/mailman/listinfo/grass-user > >
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