Geografic-Information-System/scripts/db.univar/db.univar.py

#!/usr/bin/env python

############################################################################
#
# MODULE:	db.univar (formerly called v.univar.sh)
# AUTHOR(S):	Michael Barton, Arizona State University
#               Converted to Python by Glynn Clements
#               Sync'ed to r.univar by Markus Metz
# PURPOSE:	Calculates univariate statistics from a GRASS vector map attribute column.
#               Based on r.univar.sh by Markus Neteler
# COPYRIGHT:	(C) 2005, 2007, 2008 by the GRASS Development Team
#
#		This program is free software under the GNU General Public
#		License (>=v2). Read the file COPYING that comes with GRASS
#		for details.
#
#############################################################################

#%module
#% description: Calculates univariate statistics on selected table column.
#% keyword: database
#% keyword: statistics
#% keyword: attribute table
#%end
#%option G_OPT_DB_TABLE
#% key: table
#% required: yes
#%end
#%option G_OPT_DB_COLUMN
#% description: Name of attribute column on which to calculate statistics (must be numeric)
#% required: yes
#%end
#%option G_OPT_DB_DATABASE
#%end
#%option G_OPT_DB_DRIVER
#% options: dbf,odbc,ogr,sqlite,pg
#%end
#%option G_OPT_DB_WHERE
#%end
#%option
#% key: percentile
#% type: double
#% description: Percentile to calculate (requires extended statistics flag)
#% required : no
#% answer: 90
#% options: 0-100
#% multiple: yes
#%end
#%flag
#% key: e
#% description: Extended statistics (quartiles and 90th percentile)
#%end
#%flag
#% key: g
#% description: Print stats in shell script style
#%end

import sys
import atexit
import math

import grass.script as gscript


def cleanup():
    for ext in ['', '.sort']:
        gscript.try_remove(tmp + ext)


def sortfile(infile, outfile):
    inf = file(infile, 'r')
    outf = file(outfile, 'w')

    if gscript.find_program('sort', '--help'):
        gscript.run_command('sort', flags='n', stdin=inf, stdout=outf)
    else:
        # FIXME: we need a large-file sorting function
        gscript.warning(_("'sort' not found: sorting in memory"))
        lines = inf.readlines()
        for i in range(len(lines)):
            lines[i] = float(lines[i].rstrip('\r\n'))
        lines.sort()
        for line in lines:
            outf.write(str(line) + '\n')

    inf.close()
    outf.close()


def main():
    global tmp
    tmp = gscript.tempfile()

    extend = flags['e']
    shellstyle = flags['g']
    table = options['table']
    column = options['column']
    database = options['database']
    driver = options['driver']
    where = options['where']
    perc = options['percentile']

    perc = [float(p) for p in perc.split(',')]

    desc_table = gscript.db_describe(table, database=database, driver=driver)
    if not desc_table:
        gscript.fatal(_("Unable to describe table <%s>") % table)
    found = False
    for cname, ctype, cwidth in desc_table['cols']:
        if cname == column:
            found = True
            if ctype not in ('INTEGER', 'DOUBLE PRECISION'):
                gscript.fatal(_("Column <%s> is not numeric") % cname)
    if not found:
        gscript.fatal(_("Column <%s> not found in table <%s>") % (column, table))

    if not shellstyle:
        gscript.verbose(_("Calculation for column <%s> of table <%s>..."
                          ) % (column, table))
        gscript.message(_("Reading column values..."))

    sql = "SELECT %s FROM %s" % (column, table)
    if where:
        sql += " WHERE " + where

    if not database:
        database = None

    if not driver:
        driver = None

    tmpf = file(tmp, 'w')
    gscript.run_command('db.select', flags='c', table=table,
                        database=database, driver=driver, sql=sql,
                        stdout=tmpf)
    tmpf.close()

    # check if result is empty
    tmpf = file(tmp)
    if tmpf.read(1) == '':
        gscript.fatal(_("Table <%s> contains no data.") % table)
        tmpf.close()

    # calculate statistics
    if not shellstyle:
        gscript.verbose(_("Calculating statistics..."))

    N = 0
    sum = 0.0
    sum2 = 0.0
    sum3 = 0.0
    minv = 1e300
    maxv = -1e300

    tmpf = file(tmp)
    for line in tmpf:
        if len(line.rstrip('\r\n')) == 0:
            continue
        x = float(line.rstrip('\r\n'))
        N += 1
        sum += x
        sum2 += x * x
        sum3 += abs(x)
        maxv = max(maxv, x)
        minv = min(minv, x)
    tmpf.close()

    if N <= 0:
        gscript.fatal(_("No non-null values found"))

    if not shellstyle:
        sys.stdout.write("Number of values: %d\n" % N)
        sys.stdout.write("Minimum: %.15g\n" % minv)
        sys.stdout.write("Maximum: %.15g\n" % maxv)
        sys.stdout.write("Range: %.15g\n" % (maxv - minv))
        sys.stdout.write("Mean: %.15g\n" % (sum / N))
        sys.stdout.write(
            "Arithmetic mean of absolute values: %.15g\n" %
            (sum3 / N))
        sys.stdout.write("Variance: %.15g\n" % ((sum2 - sum * sum / N) / N))
        sys.stdout.write(
            "Standard deviation: %.15g\n" %
            (math.sqrt((sum2 - sum * sum / N) / N)))
        sys.stdout.write(
            "Coefficient of variation: %.15g\n" %
            ((math.sqrt((sum2 - sum * sum / N) / N)) /
             (math.sqrt(sum * sum) / N)))
        sys.stdout.write("Sum: %.15g\n" % sum)
    else:
        sys.stdout.write("n=%d\n" % N)
        sys.stdout.write("min=%.15g\n" % minv)
        sys.stdout.write("max=%.15g\n" % maxv)
        sys.stdout.write("range=%.15g\n" % (maxv - minv))
        sys.stdout.write("mean=%.15g\n" % (sum / N))
        sys.stdout.write("mean_abs=%.15g\n" % (sum3 / N))
        sys.stdout.write("variance=%.15g\n" % ((sum2 - sum * sum / N) / N))
        sys.stdout.write(
            "stddev=%.15g\n" %
            (math.sqrt(
                (sum2 - sum * sum / N) / N)))
        sys.stdout.write(
            "coeff_var=%.15g\n" %
            ((math.sqrt((sum2 - sum * sum / N) / N)) /
             (math.sqrt(sum * sum) / N)))
        sys.stdout.write("sum=%.15g\n" % sum)

    if not extend:
        return

    # preparations:
    sortfile(tmp, tmp + ".sort")

    odd = N % 2
    eostr = ['even', 'odd'][odd]

    q25pos = round(N * 0.25)
    if q25pos == 0:
        q25pos = 1
    q50apos = round(N * 0.50)
    if q50apos == 0:
        q50apos = 1
    q50bpos = q50apos + (1 - odd)
    q75pos = round(N * 0.75)
    if q75pos == 0:
        q75pos = 1

    ppos = {}
    pval = {}
    for i in range(len(perc)):
        ppos[i] = round(N * perc[i] / 100)
        if ppos[i] == 0:
            ppos[i] = 1
        pval[i] = 0

    inf = file(tmp + ".sort")
    l = 1
    for line in inf:
        if l == q25pos:
            q25 = float(line.rstrip('\r\n'))
        if l == q50apos:
            q50a = float(line.rstrip('\r\n'))
        if l == q50bpos:
            q50b = float(line.rstrip('\r\n'))
        if l == q75pos:
            q75 = float(line.rstrip('\r\n'))
        for i in range(len(ppos)):
            if l == ppos[i]:
                pval[i] = float(line.rstrip('\r\n'))
        l += 1

    q50 = (q50a + q50b) / 2

    if not shellstyle:
        sys.stdout.write("1st Quartile: %.15g\n" % q25)
        sys.stdout.write("Median (%s N): %.15g\n" % (eostr, q50))
        sys.stdout.write("3rd Quartile: %.15g\n" % q75)
        for i in range(len(perc)):
            if perc[i] == int(perc[i]):  # integer
                if int(perc[i]) % 10 == 1 and int(perc[i]) != 11:
                    sys.stdout.write(
                        "%dst Percentile: %.15g\n" %
                        (int(
                            perc[i]),
                            pval[i]))
                elif int(perc[i]) % 10 == 2 and int(perc[i]) != 12:
                    sys.stdout.write(
                        "%dnd Percentile: %.15g\n" %
                        (int(
                            perc[i]),
                            pval[i]))
                elif int(perc[i]) % 10 == 3 and int(perc[i]) != 13:
                    sys.stdout.write(
                        "%drd Percentile: %.15g\n" %
                        (int(
                            perc[i]),
                            pval[i]))
                else:
                    sys.stdout.write(
                        "%dth Percentile: %.15g\n" %
                        (int(
                            perc[i]),
                            pval[i]))
            else:
                sys.stdout.write(
                    "%.15g Percentile: %.15g\n" %
                    (perc[i], pval[i]))
    else:
        sys.stdout.write("first_quartile=%.15g\n" % q25)
        sys.stdout.write("median=%.15g\n" % q50)
        sys.stdout.write("third_quartile=%.15g\n" % q75)
        for i in range(len(perc)):
            percstr = "%.15g" % perc[i]
            percstr = percstr.replace('.', '_')
            sys.stdout.write("percentile_%s=%.15g\n" % (percstr, pval[i]))

if __name__ == "__main__":
    options, flags = gscript.parser()
    atexit.register(cleanup)
    main()