1v.rast.stats(1)               Grass User's Manual              v.rast.stats(1)
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NAME

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

KEYWORDS

10       vector, statistics, raster, univariate  statistics,  zonal  statistics,
11       sampling, querying
12

SYNOPSIS

14       v.rast.stats
15       v.rast.stats --help
16       v.rast.stats   [-cd]   map=name    [layer=string]     [where=sql_query]
17       raster=name[,name,...]                column_prefix=string[,string,...]
18       [method=string[,string,...]]   [percentile=integer]   [--help]  [--ver‐
19       bose]  [--quiet]  [--ui]
20
21   Flags:
22       -c
23           Continue if upload column(s) already exist
24
25       -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
30       --help
31           Print usage summary
32
33       --verbose
34           Verbose module output
35
36       --quiet
37           Quiet module output
38
39       --ui
40           Force launching GUI dialog
41
42   Parameters:
43       map=name [required]
44           Name of vector map
45           Or data source for direct OGR access
46
47       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
51           access this is the layer name.
52           Default: 1
53
54       where=sql_query
55           WHERE conditions of SQL statement without ’where’ keyword
56           Example: income < 1000 and population >= 10000
57
58       raster=name[,name,...] [required]
59           Name of input raster map to calculate statistics from
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61       column_prefix=string[,string,...] [required]
62           Column prefix for new attribute columns
63
64       method=string[,string,...]
65           The methods to use
66           Options: number, null_cells, minimum, maximum, range, average, std‐
67           dev, variance, coeff_var, sum, first_quartile, median,  third_quar‐
68           tile, percentile
69           Default:       number,null_cells,minimum,maximum,range,average,std‐
70           dev,variance,coeff_var,sum,first_quartile,median,third_quar‐
71           tile,percentile
72
73       percentile=integer
74           Percentile to calculate
75           Options: 0-100
76           Default: 90
77

DESCRIPTION

79       v.rast.stats  calculates  basic univariate statistics from a raster map
80       only for the parts covered by the specified vector map.  The vector map
81       will  be  rasterized according to the raster map resolution.  Then uni‐
82       variate statistics are calculated per vector category  (cat)  from  the
83       raster  map and the results uploaded to the vector map attribute table.
84       A new column is generated in the attribute  table  for  each  statistic
85       requested in method (if not already present).
86
87       The  univariate  statistics include the number of raster cells counted,
88       the number of raster NULL cells counted, minimum and maximum cell  val‐
89       ues, range, average, standard deviation, variance, coefficient of vari‐
90       ation, sum, first quartile, median, third quartile, and percentile.
91

NOTES

93       v.rast.stats is only meaningful for lines or polygons.
94
95       The module may take a long time to run if the raster region contains  a
96       large  number  of cells. In this case the --verbose flag may be used to
97       track progress.
98
99       The script stops if a (prefixed) upload column is  already  present  in
100       the vector map attribute table, unless otherwise instructed with the -c
101       continue flag. The column prefix will be separated from  the  statistic
102       name  with  an  underscore. For example with a prefix of "elev" the sum
103       column will be named elev_sum.
104
105       If a DBF database is being used, note that column names are  restricted
106       by  the  DBF specification to 10 characters. Therefore it is advised to
107       be economical in the use of the column prefix when  using  DBF  as  any
108       additional characters will be chopped off.
109
110       If  a  MASK  is present, it will be restored after the script finished.
111       The script changes temporarily to the resolution of  the  given  raster
112       map.
113
114       Large  amounts  of  system  memory can be used when extended statistics
115       (first_quartile,median,third_quartile,percentile ) are being  requested
116       with a very large region setting. If the region is too large the module
117       should display memory allocation errors. Basic statistics can be calcu‐
118       lated using any size input region.
119

EXAMPLES

121       Example  to  upload  DEM statistics to ZIP codes vector map (North Car‐
122       olina sample dataset):
123       g.copy vect=zipcodes_wake,myzipcodes_wake
124       # set computational region to DEM:
125       g.region raster=elevation -p
126       # calculate selected DEM statistics, upload to vector map table:
127       v.rast.stats myzipcodes_wake raster=elevation \
128         column_prefix=elev method=minimum,maximum,average,range,stddev,percentile \
129         percentile=95
130       # verify results:
131       v.info -c myzipcodes_wake
132       v.db.select myzipcodes_wake
133       v.univar myzipcodes_wake column=elev_range type=centroid
134

SEE ALSO

136          r.univar,   v.univar,   v.vect.stats,   v.what.rast,   v.what.rast3,
137       v.what.vect
138

AUTHOR

140       Markus Neteler, CEA (for the EDEN EU/FP6 Project)
141
142       Last changed: $Date: 2018-05-03 22:08:30 +0200 (Thu, 03 May 2018) $
143

SOURCE CODE

145       Available at: v.rast.stats source code (history)
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147       Main  index  | Vector index | Topics index | Keywords index | Graphical
148       index | Full index
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150       © 2003-2019 GRASS Development Team, GRASS GIS 7.6.0 Reference Manual
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154GRASS 7.6.0                                                    v.rast.stats(1)
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