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v.normal

Tests for normality for vector points.

v.normal [-rl] map=name [layer=string] tests=range [,range,...] column=name [--verbose] [--quiet] [--qq] [--ui]

Example:

v.normal map=name tests=range column=name

grass.script.run_command("v.normal", map, layer="1", tests, column, flags=None, verbose=False, quiet=False, superquiet=False)

Example:

gs.run_command("v.normal", map="name", tests="range", column="name")

Parameters

map=name [required]
    Name of vector map
    Or data source for direct OGR access
layer=string
    Layer number or name
    Vector features can have category values in different layers. This number determines which layer to use. When used with direct OGR access this is the layer name.
    Default: 1
tests=range [,range,...] [required]
    Lists of tests (1-15)
    E.g. 1,3-8,13
column=name [required]
    Name of attribute column
-r
    Use only points in current region
-l
    Lognormality instead of normality
--help
    Print usage summary
--verbose
    Verbose module output
--quiet
    Quiet module output
--qq
    Very quiet module output
--ui
    Force launching GUI dialog

map : str, required
    Name of vector map
    Or data source for direct OGR access
    Used as: input, vector, name
layer : str, optional
    Layer number or name
    Vector features can have category values in different layers. This number determines which layer to use. When used with direct OGR access this is the layer name.
    Used as: input, layer
    Default: 1
tests : str | list[str], required
    Lists of tests (1-15)
    E.g. 1,3-8,13
    Used as: range
column : str, required
    Name of attribute column
    Used as: input, dbcolumn, name
flags : str, optional
    Allowed values: r, l
    r
        Use only points in current region
    l
        Lognormality instead of normality
verbose: bool, optional
    Verbose module output
    Default: False
quiet: bool, optional
    Quiet module output
    Default: False
superquiet: bool, optional
    Very quiet module output
    Default: False

DESCRIPTION

v.normal computes tests of normality on vector points.

NOTES

The tests that v.normal performs are indexed below. The tests that are performed are specified by giving an index, ranges of indices, or multiple thereof.

  1. Sample skewness and kurtosis
  2. Geary's a-statistic and an approximate normal transformation
  3. Extreme normal deviates
  4. D'Agostino's D-statistic
  5. Modified Kuiper V-statistic
  6. Modified Watson U^2-statistic
  7. Durbin's Exact Test (modified Kolmogorov)
  8. Modified Anderson-Darling statistic
  9. Modified Cramer-Von Mises W^2-statistic
  10. Kolmogorov-Smirnov D-statistic (modified for normality testing)
  11. Chi-Square test statistic (equal probability classes) and the number of degrees of freedom
  12. Shapiro-Wilk W Test
  13. Weisberg-Binghams W'' (similar to Shapiro-Francia's W')
  14. Royston's extension of W for large samples
  15. Kotz Separate-Families Test for Lognormality vs. Normality

EXAMPLE

Compute the sample skewness and kurtosis, Geary's a-statistic and an approximate normal transformation, extreme normal deviates, and Royston's W for the random vector points:

g.region raster=elevation -p
v.random random n=200
v.db.addtable random column="elev double precision"
v.what.rast random rast=elevation column=elev
v.normal random tests=1-3,14 column=elev

SEE ALSO

v.univar

AUTHORS

James Darrell McCauley \<darrell@mccauley-usa.com>,
when he was at: Agricultural Engineering Purdue University

SOURCE CODE

Available at: v.normal source code (history)
Latest change: Friday Feb 07 19:16:09 2025 in commit a82a39f