1v.rast.stats(1) GRASS GIS User's Manual v.rast.stats(1)
2
6 v.rast.stats - Calculates univariate statistics from a raster map
7 based on a vector map and uploads statistics to new attribute columns.
8
10 vector, statistics, raster, univariate statistics, zonal statistics,
11 sampling, querying
12
14 v.rast.stats
15 v.rast.stats --help
16 v.rast.stats [-cd] map=name [layer=string]
17 [type=string[,string,...]] [where=sql_query] raster=name[,name,...]
18 column_prefix=string[,string,...] [method=string[,string,...]] [per‐
19 centile=integer] [--help] [--verbose] [--quiet] [--ui]
20 Flags:
22 -c
23 Continue if upload column(s) already exist
24 -d
26 Create densified lines (default: thin lines)
27 All cells touched by the line will be set, not only those on the
28 render path
29 --help
31 Print usage summary
32 --verbose
34 Verbose module output
35 --quiet
37 Quiet module output
38 --ui
40 Force launching GUI dialog
41 Parameters:
43 map=name [required]
44 Name of vector map
45 Or data source for direct OGR access
46 layer=string
48 Layer number or name
49 Vector features can have category values in different layers. This
50 number determines which layer to use. When used with direct OGR ac‐
51 cess this is the layer name.
52 Default: 1
53 type=string[,string,...]
55 Input feature type
56 Options: point, line, boundary, centroid, area
57 Default: point,line,boundary,centroid,area
58 where=sql_query
60 WHERE conditions of SQL statement without ’where’ keyword
61 Example: income < 1000 and population >= 10000
62 raster=name[,name,...]Â [required]
64 Name of input raster map to calculate statistics from
65 column_prefix=string[,string,...]Â [required]
67 Column prefix for new attribute columns
68 method=string[,string,...]
70 The methods to use
71 Options: number, null_cells, minimum, maximum, range, average, std‐
72 dev, variance, coeff_var, sum, first_quartile, median, third_quar‐
73 tile, percentile
74 Default: number,null_cells,minimum,maximum,range,average,std‐
75 dev,variance,coeff_var,sum,first_quartile,median,third_quar‐
76 tile,percentile
77 percentile=integer
79 Percentile to calculate
80 Options: 0-100
81 Default: 90
82
84 v.rast.stats calculates basic univariate statistics from a raster map
85 only for the parts covered by the specified vector map. The vector map
86 will be rasterized according to the raster map resolution. Then uni‐
87 variate statistics are calculated per vector category (cat) from the
88 raster map and the results uploaded to the vector map attribute table.
89 A new column is generated in the attribute table for each statistic re‐
90 quested in method (if not already present).
91 The univariate statistics include the number of raster cells counted,
93 the number of raster NULL cells counted, minimum and maximum cell val‐
94 ues, range, average, standard deviation, variance, coefficient of vari‐
95 ation, sum, first quartile, median, third quartile, and percentile.
96
98 v.rast.stats is only meaningful for lines or polygons.
99 The module may take a long time to run if the raster region contains a
101 large number of cells. In this case the --verbose flag may be used to
102 track progress.
103 The script stops if a (prefixed) upload column is already present in
105 the vector map attribute table, unless otherwise instructed with the -c
106 continue flag. The column prefix will be separated from the statistic
107 name with an underscore. For example with a prefix of "elev" the sum
108 column will be named elev_sum.
109 If a DBF database is being used, note that column names are restricted
111 by the DBF specification to 10 characters. Therefore it is advised to
112 be economical in the use of the column prefix when using DBF as any ad‐
113 ditional characters will be chopped off.
114 If a MASK is present, it will be restored after the script finished.
116 The script changes temporarily to the resolution of the given raster
117 map.
118 If an area has several categories in the selected layer (equivalent to
120 overlapping polygons in Simple Features), only one category will be
121 kept during the rasterization process. Statistics for the skipped cate‐
122 gories will thus be partial.
123 For example, if there are three areas: area 1 with cat 1, area 2 with
125 cat 2, area 3 with cats 1, 2. Only one category value of area 3 will be
126 used for rasterization, the other category value will be skipped. Thus
127 statistics for the used category value will be complete, while statis‐
128 tics for the skipped category value will be incomplete.
129 Large amounts of system memory can be used when extended statistics
131 (first_quartile,median,third_quartile,percentile ) are being requested
132 with a very large region setting. If the region is too large the module
133 should display memory allocation errors. Basic statistics can be calcu‐
134 lated using any size input region.
135
137 Example to upload DEM statistics to ZIP codes vector map (North Car‐
138 olina sample dataset):
139 g.copy vect=zipcodes_wake,myzipcodes_wake
140 # set computational region to DEM:
141 g.region raster=elevation -p
142 # calculate selected DEM statistics, upload to vector map table:
143 v.rast.stats myzipcodes_wake raster=elevation \
144 column_prefix=elev method=minimum,maximum,average,range,stddev,percentile \
145 percentile=95
146 # verify results:
147 v.info -c myzipcodes_wake
148 v.db.select myzipcodes_wake
149 v.univar myzipcodes_wake column=elev_range type=centroid
150
152 r.univar, v.univar, v.vect.stats, v.what.rast, v.what.rast3,
153 v.what.vect
154
156 Markus Neteler, CEA (for the EDEN EU/FP6 Project)
157
159 Available at: v.rast.stats source code (history)
160 Accessed: Mon Jun 20 16:47:46 2022
162 Main index | Vector index | Topics index | Keywords index | Graphical
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165 © 2003-2022 GRASS Development Team, GRASS GIS 8.2.0 Reference Manual
167GRASS 8.2.0 v.rast.stats(1)