QGIS/python/plugins/processing/algs/qgis/MeanAndStdDevPlot.py

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

"""
***************************************************************************
    MeanAndStdDevPlot.py
    ---------------------
    Date                 : January 2013
    Copyright            : (C) 2013 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__ = 'January 2013'
__copyright__ = '(C) 2013, Victor Olaya'

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

__revision__ = '$Format:%H$'

import matplotlib.pyplot as plt
import matplotlib.pylab as lab
import numpy as np

from PyQt4.QtCore import *
from qgis.core import *

from processing.core.GeoAlgorithm import GeoAlgorithm
from processing.core.parameters import ParameterTable
from processing.core.parameters import ParameterTableField
from processing.core.outputs import OutputHTML

from processing.tools import vector
from processing.tools import dataobjects


class MeanAndStdDevPlot(GeoAlgorithm):

    INPUT = 'INPUT'
    OUTPUT = 'OUTPUT'
    NAME_FIELD = 'NAME_FIELD'
    MEAN_FIELD = 'MEAN_FIELD'
    STDDEV_FIELD = 'STDDEV_FIELD'

    def defineCharacteristics(self):
        self.name = 'Mean and standard deviation plot'
        self.group = 'Graphics'

        self.addParameter(ParameterTable(self.INPUT,
            self.tr('Input table')))
        self.addParameter(ParameterTableField(self.NAME_FIELD,
            self.tr('Category name field'), self.INPUT,
            ParameterTableField.DATA_TYPE_ANY))
        self.addParameter(ParameterTableField(self.MEAN_FIELD,
            self.tr('Mean field'), self.INPUT))
        self.addParameter(ParameterTableField(self.STDDEV_FIELD,
            self.tr('StdDev field'), self.INPUT))

        self.addOutput(OutputHTML(self.OUTPUT, self.tr('Output')))

    def processAlgorithm(self, progress):
        layer = dataobjects.getObjectFromUri(
            self.getParameterValue(self.INPUT))
        namefieldname = self.getParameterValue(self.NAME_FIELD)
        meanfieldname = self.getParameterValue(self.MEAN_FIELD)
        stddevfieldname = self.getParameterValue(self.STDDEV_FIELD)

        output = self.getOutputValue(self.OUTPUT)

        values = vector.values(layer, namefieldname, meanfieldname, stddevfieldname)
        plt.close()
        ind = np.arange(len(values[namefieldname]))
        width = 0.8
        plt.bar(ind, values[meanfieldname], width, color='r',
                yerr=values[stddevfieldname],
                error_kw=dict(ecolor='yellow'),
               )

        plt.xticks(ind, values[namefieldname], rotation=45)
        plotFilename = output + '.png'
        lab.savefig(plotFilename)
        f = open(output, 'w')
        f.write('<img src="' + plotFilename + '"/>')
        f.close()