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

[Micha Silver]

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@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@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, ...). For r.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 list grass-user@lists.osgeo.org https://lists.osgeo.org/mailman/listinfo/grass-user -- Micha Silver Ben Gurion Univ. Sde Boker, Remote Sensing Lab cell: +972-523-665918 https://orcid.org/0000-0002-1128-1325

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