Often you will wish to see statistics summarizing the data that is contained in your maps. GRASS offers several modules that allow you to do this.
Get summary information about a single raster map
r.cats - Prints category values and labels associated with user-specified raster map layers.
r.describe - Prints terse list of category values found in a raster map layer.
r.info - Outputs basic information about a user-specified raster map layer
r.report - Reports acres, hectares, or number of cells as well as miles, meters, or kilometer for each category in a raster map layer.
r.info - Generates area statistics for raster map layers. Can print total area, number of cells, percent cover for each category. Can also print category value, row, and column, as well as easting and northing for each cell.
r.sum - Sums up the raster cell values.
r.univar - Univariate statistics for a GRASS raster map
r.surf.area - Surface area estimation for rasters.
Get information about a single raster map at specific points
d.what.rast - Allows the user to interactively query the category contents of multiple raster map layers at user-specified locations within the current geographic region.
r.what - Queries raster map layers on their category values and category labels at specific easting and northing locations, which are typed in.
s.sample - Sample a raster file at site locations.
Get information about a single raster map along transects or profiles
Get information from two or more raster maps
Given a base map, get information for corresponding areas in a cover map
r.average - Finds the average of values in a cover map within areas assigned the same category value in a user-specified base map.
r.median - Finds the median of values in a cover map within areas assigned the same category value in a user-specified base map
r.mode - Finds the mode of values in a cover map within areas assigned the same category value in a user-specified base map
r.statistics - Category or object oriented statistics. Can calculate distribution, average, mode, median, standard deviation, variance, skewness, kurtosis, minimum, maximum, and sum for cells in a cover map given categories in a user-specified base map.
r.volume - Calculates the volume of data "clumps", and (optionally) produces a GRASS site_lists file containing the calculated centroids of these clumps.
Quantify the relationship between two or more raster maps
r.coin - Tabulates the mutual occurrence (coincidence) of categories for two raster map layers.
r.covar - Outputs a covariance/correlation matrix for user-specified raster map layer(s).
r.distance - Locates the closest points between objects in two raster maps.
m.ipf - Iterative proportional fitting for error matrices. Uses an error or confusion matrix produced by r.coin or r.kappa, smooths zero counts, and does iterative proportional fitting to normalize the matrix.
Get summary information about a single vector map
v.info - Information about a vector map's boundaries, projection, data type, category number, data base location and mapset, and history are put into a table and written to standard output.
v.report - Generates a table showing the area present in each of the categories of a user-selected data layer. Area is given in hectares, square meters, and square kilometers
v.stats - Prints information about a binary GRASS vector map layer. Information includes the number of lines, nodes, areas, islands, and attributes.
Get information about a single vector map at specific points or in specific areas
v.area - Display GRASS area and perimeter information for GRASS vector map. Then user can select area on map by clicking with mouse within the desired area. Selected area will be highlighted in selected color on graphics display. On regular screen area infomation will be displayed, in square meters, hectares, acres, and square miles, Perimeter measurements, in meters, feet, and miles, are also displayed.
v.distance - Calculate the distance from a point to the nearest line or point in a vector map. User types in easting and northing coordinates.
v.what - Query the category contents of a (binary) vector map layer at user-selected locations. The mouse can be used or easting and northing can be typed.