[GRASS-user] SQL: generating numeric class numbers from class text labels?

[Markus Neteler]

Thanks for your answers.
In fact I need it in Python...

Best
Markus


Micha Silver <tsvibar at gmail.com> schrieb am Mi., 4. Dez. 2019, 18:57:

> How about doing this in R? The labels will be read into R as factors, and
> the factor levels can easily be extracted as numbers.
>
>
> Something like this:
>
>
> micha at tp480:~$ v.info -c stations
> Displaying column types/names for database connection of layer <1>:
> INTEGER|cat
> INTEGER|station_num
> TEXT|station_he
> TEXT|station_en
> TEXT|type
> INTEGER|x_coord
> INTEGER|y_coord
> DOUBLE PRECISION|long
> DOUBLE PRECISION|lat
> INTEGER|elev
> TEXT|date_open
> DOUBLE PRECISION|dist
> DOUBLE PRECISION|azim
>
>
> micha at tp480:~$ R
>
>
> R version 3.5.2 (2018-12-20) -- "Eggshell Igloo"
> Copyright (C) 2018 The R Foundation for Statistical Computing
> Platform: x86_64-pc-linux-gnu (64-bit)
> .....
>
> > library(rgrass7)
> Loading required package: XML
> GRASS GIS interface loaded with GRASS version: GRASS 7.6.0 (2019)
> and location: ITM
> > use_sf()
> > stations = readVECT("stations")
> WARNING: Vector map <stations> is 3D. Use format specific layer creation
>          options (parameter 'lco') to export <in 3D rather than 2D
>          (default).
> Exporting 94 features...
>  100%
> .....
>
> > stations['new_station_num'] = as.numeric(stations$station_en)
> > stations$new_station_num
>  [1] 71 26  6 55 54 63  7  8 31 30 46 84 92 38 32 88 27 12 67 62 47 33 53
> 76 89
> [26]  2 86 11 40 65 64 45 13 85 60 59  1 74 73 22 19 15 39 50 56 14 44 23
> 36 83
> [51] 41 42 43 18 17 75 16 82 81 37 48 28 87  3 66 10 34 91 61 93 94 72  5
> 4 68
> [76] 78 77  9 29 51 58 57 49 52 24 25 80 79 35 70 69 90 21 20
>
> > writeVECT(SDF=stations, vname="new_stations")
>
>
> Best regards, Micha
>
>
> On 04/12/2019 19:11, Markus Neteler wrote:
>
> Hi,
>
> I have a landuse map with text labels (forest, street, ...). Forr.learn.ml I need to have them as numeric classes.
> It is not important for me which number is assigned but I search for
> an automated solution, i.e. SQL statement unless there is a different
> way.
>
> So:
>
> cat|label|label_int
> 1|forest|1
> 2|forest|1
> 3|street|2
> 4|forest|1
> 5|street|2
> 6|urban|3
> ...
>
> I guess I have done that already some years ago but I can't remember
> the trick :-)
>
> thanks for a hint,
> Markus
> _______________________________________________
> grass-user mailing listgrass-user at lists.osgeo.orghttps://lists.osgeo.org/mailman/listinfo/grass-user
>
> --
> Micha Silver
> Ben Gurion Univ.
> Sde Boker, Remote Sensing Lab
> cell: +972-523-665918https://orcid.org/0000-0002-1128-1325
>
>
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