![]() Open Source GIS: A GRASS GIS Approach, p. Here's an example of how you could use r.stats and r.reclass to assign the total area size in square meters of each category to each cell of that respective category: r.stats -qan in=map | awk '' | r.reclass in=map out=newmap Notes You might wish to automate the assigning of labels. spatial database queries and to create the graphicoutput for map files. ![]() To finish, just type 'end' at the "Next category" prompt. Waputik lootely - N Little roho R Yoho YOHO Talable Falls NATIONAL PARK River. ![]() In this example, a dataset of land surface. To go on to the next screen of the editor, type ESC-RETURN again. A raster object can be created by calling the rast() function and specifying an external image file as an argument. You normally don't want to change that, so just go on by typing ESC-RETURN to enter the category table 'editor'. You will get to a screen showing the highest category number. After selecting the raster to be reclassified, simply scroll to the bottom of the dialog, ensure the box replace no data values box is checked. Enter 'y' when you get to the question "Edit the category file for ?". The simplest one-step and, IMO, most consistently reliable solution to reclassifying NoData to zero is to use the Reclassify Grid Values tool (SAGA) in the processing toolbox. R.clump : Recategorizes data in a raster map layer by grouping cells that form physically discrete areas into unique categoriesįor changing the category labels of a raster map, use r.support. R.mapcalc : Raster map layer data calculator (see the chapter called Raster map algrebra with r.mapcalc for more detailed information) R.rescale : Rescales the range of category values in a raster map layer (also see r.rescale.eq and r.rescale.inf R.recode : Creates an output map layer based on an input raster map layer R.reclass : Creates a new (pseudo-)map layer whose category values are based upon the user's reclassification of categories in an existing raster map layer In order to create a new map by changing the category values of an already existing one, you can use the following modules: Actually the first is not really possible without creating a new map, dropping the old one and renaming the new one to the old one's name. You have to distinguish between changing the category values of a map and changing the category labels. Often times, during spatial analysis using raster data, there might be a need to change a particular value in the data to different value to use the raster.
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