code/train/Python/0023545_BasicStatisticsStrings.py

# -*- coding: utf-8 -*-

"""
***************************************************************************
    BasicStatisticsStrings.py
    ---------------------
    Date                 : September 2012
    Copyright            : (C) 2012 by Victor Olaya
    Email                : volayaf at gmail dot com
***************************************************************************
*                                                                         *
*   This program is free software; you can redistribute it and/or modify  *
*   it under the terms of the GNU General Public License as published by  *
*   the Free Software Foundation; either version 2 of the License, or     *
*   (at your option) any later version.                                   *
*                                                                         *
***************************************************************************
"""

__author__ = 'Victor Olaya'
__date__ = 'September 2012'
__copyright__ = '(C) 2012, Victor Olaya'

# This will get replaced with a git SHA1 when you do a git archive

__revision__ = '$Format:%H$'

import codecs
from PyQt4.QtCore import *
from qgis.core import *
from processing.core.GeoAlgorithm import GeoAlgorithm
from processing.core.parameters import ParameterVector
from processing.core.parameters import ParameterTableField
from processing.core.outputs import OutputHTML
from processing.core.outputs import OutputNumber
from processing.tools import dataobjects, vector


class BasicStatisticsStrings(GeoAlgorithm):

    INPUT_LAYER = 'INPUT_LAYER'
    FIELD_NAME = 'FIELD_NAME'
    OUTPUT_HTML_FILE = 'OUTPUT_HTML_FILE'

    MIN_LEN = 'MIN_LEN'
    MAX_LEN = 'MAX_LEN'
    MEAN_LEN = 'MEAN_LEN'
    COUNT = 'COUNT'
    EMPTY = 'EMPTY'
    FILLED = 'FILLED'
    UNIQUE = 'UNIQUE'

    def defineCharacteristics(self):
        self.name = 'Basic statistics for text fields'
        self.group = 'Vector table tools'

        self.addParameter(ParameterVector(self.INPUT_LAYER,
                          'Input vector layer',
                          ParameterVector.VECTOR_TYPE_ANY, False))
        self.addParameter(ParameterTableField(self.FIELD_NAME,
                          'Field to calculate statistics on',
                          self.INPUT_LAYER,
                          ParameterTableField.DATA_TYPE_STRING))

        self.addOutput(OutputHTML(self.OUTPUT_HTML_FILE,
                       'Statistics for text field'))

        self.addOutput(OutputNumber(self.MIN_LEN, 'Minimum length'))
        self.addOutput(OutputNumber(self.MAX_LEN, 'Maximum length'))
        self.addOutput(OutputNumber(self.MEAN_LEN, 'Mean length'))
        self.addOutput(OutputNumber(self.COUNT, 'Count'))
        self.addOutput(OutputNumber(self.EMPTY, 'Number of empty values'))
        self.addOutput(OutputNumber(self.FILLED, 'Number of non-empty values'))
        self.addOutput(OutputNumber(self.UNIQUE, 'Number of unique values'))

    def processAlgorithm(self, progress):
        layer = dataobjects.getObjectFromUri(
                self.getParameterValue(self.INPUT_LAYER))
        fieldName = self.getParameterValue(self.FIELD_NAME)

        outputFile = self.getOutputValue(self.OUTPUT_HTML_FILE)

        index = layer.fieldNameIndex(fieldName)

        sumValue = 0
        minValue = 0
        maxValue = 0
        meanValue = 0
        countEmpty = 0
        countFilled = 0

        isFirst = True
        values = []

        features = vector.features(layer)
        count = len(features)
        total = 100.0 / float(count)
        current = 0
        for ft in features:
            length = float(len(ft.attributes()[index]))

            if isFirst:
                minValue = length
                maxValue = length
                isFirst = False
            else:
                if length < minValue:
                    minValue = length
                if length > maxValue:
                    maxValue = length

            if length != 0.00:
                countFilled += 1
            else:
                countEmpty += 1

            values.append(length)
            sumValue += length

            current += 1
            progress.setPercentage(int(current * total))

        n = float(len(values))
        if n > 0:
            meanValue = sumValue / n

        uniqueValues = vector.getUniqueValuesCount(layer, index)

        data = []
        data.append('Minimum length: ' + unicode(minValue))
        data.append('Maximum length: ' + unicode(maxValue))
        data.append('Mean length: ' + unicode(meanValue))
        data.append('Filled: ' + unicode(countFilled))
        data.append('Empty: ' + unicode(countEmpty))
        data.append('Count: ' + unicode(count))
        data.append('Unique: ' + unicode(uniqueValues))

        self.createHTML(outputFile, data)

        self.setOutputValue(self.MIN_LEN, minValue)
        self.setOutputValue(self.MAX_LEN, maxValue)
        self.setOutputValue(self.MEAN_LEN, meanValue)
        self.setOutputValue(self.FILLED, countFilled)
        self.setOutputValue(self.EMPTY, countEmpty)
        self.setOutputValue(self.COUNT, count)
        self.setOutputValue(self.UNIQUE, uniqueValues)

    def createHTML(self, outputFile, algData):
        f = codecs.open(outputFile, 'w', encoding='utf-8')
        f.write('<html><head>')
        f.write('<meta http-equiv="Content-Type" content="text/html; \
                charset=utf-8" /></head><body>')
        for s in algData:
            f.write('<p>' + str(s) + '</p>')
        f.write('</body></html>')
        f.close()