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# Code source de pywws.WindRose

    #!/usr/bin/env python

    # pywws - Python software for USB Wireless Weather Stations
    # http://github.com/jim-easterbrook/pywws
    # Copyright (C) 2008-13  Jim Easterbrook  jim@jim-easterbrook.me.uk

    # 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.

    # This program is distributed in the hope that it will be useful,
    # but WITHOUT ANY WARRANTY; without even the implied warranty of
    # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    # GNU General Public License for more details.

    # You should have received a copy of the GNU General Public License
    # along with this program; if not, write to the Free Software
    # Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.

    """Plot a "wind rose"

    ::

    %s

    Introduction
    ------------

    This routine plots one or more "wind roses" (see `Wikipedia
    <http://en.wikipedia.org/wiki/Wind_rose>`_ for a description). Like
    :py:mod:`pywws.Plot` almost everything is controlled by an XML
    "recipe" / template file.

    Before writing your own template files, it might be useful to look at
    some of the examples in the example_graph_templates directory. If
    (like I was) you are unfamiliar with XML, I suggest reading the `W3
    Schools XML tutorial <http://www.w3schools.com/xml/>`_.

    XML graph file syntax
    ---------------------

    Here is the simplest useful wind rose template. It plots wind over the
    last 24 hours. ::

      <?xml version="1.0" encoding="ISO-8859-1"?>
      <graph>
        <windrose>
          <ycalc>data['wind_ave']</ycalc>
        </windrose>
      </graph>

    In this example, the root element graph has one windrose element which
    contains nothing more than a ycalc element.

    The complete element hierarchy is shown below. ::

        graph
            windrose
                xcalc
                ycalc
                threshold
                colour
                yrange
                points
                source
                title
            start
            stop
            duration
            layout
            size
            fileformat
            lmargin, rmargin, tmargin, bmargin
            title

    graph
    ^^^^^

    This is the root element of the graph XML file. It does not have to be
    called "graph", but there must be exactly one root element.

    windrose
    ^^^^^^^^

    A separate plot is drawn for each windrose element, but all share the
    same time period.

    start
    ^^^^^

    This element sets the date & time of the wind roses. It is used in the
    constructor of a Python datetime object. For example, to start at noon
    (local time) on Christmas day 2008: ``<start>year=2008, month=12,
    day=25, hour=12</start>``. The default value is (stop - duration).

    stop
    ^^^^

    This element sets the date & time of the end of the wind roses. It is
    used in the constructor of a Python datetime object. For example, to
    end at 10 am (local time) on new year's day 2009: ``<stop>year=2009,
    month=1, day=1, hour=10</stop>``. The default value is (start +
    duration), unless start is not defined in which case the timestamp of
    the latest weather station hourly reading is used.

    duration
    ^^^^^^^^

    This element sets the duration of wind roses, unless both start and
    stop are defined. It is used in the constructor of a Python timedelta
    object. For example, to plot one week:
    ``<duration>weeks=1</duration>``. The default value is hours=24.

    layout
    ^^^^^^

    Controls the layout of the plots. Default is a grid that is wider than
    it is tall. The layout element specifies rows and columns. For
    example: ``<layout>4, 2</layout>`` will use a grid of 4 rows and 2
    columns.

    size
    ^^^^

    Sets the overall dimensions of the image file containing the graph.
    Default is a height of 600 pixels and a width that depends on the
    layout. Any size element must include both width and height. For
    example: ``<size>800, 600</size>`` will produce an image 800 pixels
    wide and 600 pixels high.

    fileformat
    ^^^^^^^^^^

    Sets the image format of the file containing the plots. Default is
    png. Any string recognised by your installation of gnuplot should do.
    For example: ``<fileformat>gif</fileformat>`` will produce a GIF
    image.

    lmargin, rmargin, tmargin, bmargin
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

    Over-rides the automatically computed left, right, top or bottom
    margin. Supply any positive real number, for example
    ``<lmargin>1.3</lmargin>``. Some experimentation may be necessary to
    find the best values.

    title
    ^^^^^

    Sets the overall title of the plots. A single line of text, for
    example: ``<title>Today's weather</title>``. This title appears at the
    very top, outside any plot area.

    xcalc
    ^^^^^

    Selects if data is included in the wind rose. The value should be a
    valid Python logical expression. For example, to plot a rose for
    afternoon winds only: ``<xcalc>data['idx'].hour &gt;= 12</xcalc>``.
    This allows aggregation of afternoon wind data over several days.
    Remember that data is indexed in UTC, so you need to use an expression
    that takes account of your time zone. The default value is 'True'.

    ycalc
    ^^^^^

    Selects the data to be plotted. Any one line Python expression that
    returns a single float value can be used. At its simplest this just
    selects one value from the "data" dictionary, for example:
    ``<ycalc>data['wind_ave']</ycalc>``. To convert to mph use:
    ``<ycalc>data['wind_ave'] * 3.6 / 1.609344</ycalc>``. You are unlikely
    to want to use anything other than 'wind_ave' here.

    threshold
    ^^^^^^^^^

    Sets the thresholds for each colour on the rose petals. Defaults are
    based on the Wikipedia example. The values should be a correctly
    ordered list of real numbers, for example: ``<threshold>0.5, 3.5, 7.5,
    12.5, 18.5, 24.5, 31.5</threshold>`` approximates to the Beaufort
    scale, if ycalc has been set to convert windspeeds to mph.

    colour
    ^^^^^^

    Sets the colours of the threshold petal segments. Any sequence of
    integer values is accepted. The mapping of colours to numbers is set
    by gnuplot. Default value is 0, 1, 2, 3, etc.

    yrange
    ^^^^^^

    Sets the upper limits of the axes. The rose shows what percentage of
    the time the wind came from a particular direction. For example, if
    you live somewhere with a very steady wind you might want to allow
    higher percentages than normal: ``<yrange>91</yrange>``. Auto-scaling
    is also possible, using an asterisk: ``<yrange>*</yrange>``

    points
    ^^^^^^

    Sets the text of the compass points. The defaults are 'N', 'S', 'E' &
    'W'. For graphs in another language you can over-ride this, for
    example: ``<points>'No', 'Zu', 'Oo', 'We'</points>``. (The preferred
    way to do this is to create a language file, see Localisation.py.)

    source
    ^^^^^^

    Select the weather data to be plotted. Permitted values are
    ``<source>raw</source>``, ``<source>hourly</source>``,
    ``<source>daily</source>`` and ``<source>monthly</source>``. Default
    is raw. Note that the different sources have different data
    dictionaries, so this choice affects ycalc.

    title
    ^^^^^

    Sets the title of the plot. A single line of text, for example:
    ``<title>Morning winds</title>``. This title appears within the plot
    area, above the threshold colour key.

    Detailed API
    ------------

    """

    __docformat__ = "restructuredtext en"
    __usage__ = """
     usage: python -m pywws.WindRose [options] data_dir temp_dir xml_file output_file
     options are:
      -h or --help    display this help
     data_dir is the root directory of the weather data
     temp_dir is a workspace for temporary files e.g. /tmp
     xml_file is the name of the source file that describes the plot
     output_file is the name of the image file to be created e.g. 24hrs.png
    """
    __doc__ %= __usage__
    __usage__ = __doc__.split('\n')[0] + __usage__

    import codecs
    from datetime import datetime, timedelta
    import getopt
    import math
    import os
    import sys
    import xml.dom.minidom

    from pywws.conversions import *
    from pywws import DataStore
    from pywws import Localisation
    from pywws.Plot import BasePlotter
    from pywws.TimeZone import Local

    class RosePlotter(BasePlotter):
        def GetPlotList(self):
            return self.GetChildren(self.graph, 'windrose')

        def GetDefaultRows(self):
            return int(math.sqrt(self.plot_count))

        def GetDefaultPlotSize(self):
            return 600 // self.rows, 600 // self.rows

        def GetPreamble(self):
            result = """set polar
    set angles degrees
    set xtics axis nomirror
    set ytics axis nomirror
    set zeroaxis
    set grid polar 22.5
    set size square
    unset border
    """
            lmargin = eval(self.GetValue(self.graph, 'lmargin', '-1'))
            result += 'set lmargin %g\n' % (lmargin)
            lmargin = eval(self.GetValue(self.graph, 'rmargin', '-1'))
            result += 'set rmargin %g\n' % (lmargin)
            lmargin = eval(self.GetValue(self.graph, 'tmargin', '-1'))
            result += 'set tmargin %g\n' % (lmargin)
            lmargin = eval(self.GetValue(self.graph, 'bmargin', '-1'))
            result += 'set bmargin %g\n' % (lmargin)
            return result

        def PlotData(self, plot_no, plot, source):
            _ = Localisation.translation.ugettext
            # get statistics
            thresh = eval(self.GetValue(
                plot, 'threshold', '0.0, 1.54, 3.09, 5.14, 8.23, 10.8, 15.5'))
            thresh = thresh + (1000.0,)
            colour = eval(self.GetValue(plot, 'colour', str(range(len(thresh)))))
            xcalc = self.GetValue(plot, 'xcalc', 'True')
            xcalc = compile(xcalc, '<string>', 'eval')
            ycalc = self.GetValue(plot, 'ycalc', None)
            ycalc = compile(ycalc, '<string>', 'eval')
            histograms = []
            for i in range(len(thresh)):
                hist = []
                for n in range(16):
                    hist.append(0)
                histograms.append(hist)
            # x_lo & x_hi are in local time, data is indexed in UTC
            start = self.x_lo - self.utcoffset
            stop = self.x_hi - self.utcoffset
            stop = stop + timedelta(minutes=1)
            for data in source[start:stop]:
                wind_dir = data['wind_dir']
                if wind_dir == None or wind_dir >= 16:
                    continue
                if not eval(xcalc):
                    continue
                value = eval(ycalc)
                if value is None:
                    continue
                for t in range(len(thresh)):
                    if value <= thresh[t]:
                        histograms[t][wind_dir] += 1
                        break
            # evenly distribute zero speed
            total = 0
            for n in range(16):
                total += histograms[0][n]
            for n in range(16):
                histograms[0][n] = total // 16
            # integrate histograms
            for i in range(1, len(thresh)):
                for n in range(16):
                    histograms[i][n] += histograms[i-1][n]
            total = 0
            for n in range(16):
                total += histograms[-1][n]
            result = ''
            yrange = self.GetValue(plot, 'yrange', '31')
            if yrange == '*':
                # auto-ranging
                if total > 0:
                    max_petal = 100.0 * float(max(histograms[-1])) / float(total)
                else:
                    max_petal = 0.0
                if max_petal > 40.0:
                    yrange = (int(max_petal / 20.0) * 20) + 21
                elif max_petal > 30.0:
                    yrange = 41
                elif max_petal > 20.0:
                    yrange = 31
                else:
                    yrange = 21
            else:
                yrange = eval(yrange)
            result += 'set xrange [-%d:%d]\n' % (yrange, yrange)
            result += 'set yrange [-%d:%d]\n' % (yrange, yrange)
            points = [_('N'), _('S'), _('E'), _('W')]
            points = eval(self.GetValue(plot, 'points', str(points)))
            result += 'set label 1000 "%s" at 0, %d center front\n' % (points[0], yrange)
            result += 'set label 1001 "%s" at 0, -%d center front\n' % (points[1], yrange)
            result += 'set label 1002 "%s" at %d, 0 center front\n' % (points[2], yrange)
            result += 'set label 1003 "%s" at -%d, 0 center front\n' % (points[3], yrange)
            # plot segments for each speed-direction
            result += 'plot '
            for i in reversed(range(len(thresh))):
                dat_file = os.path.join(self.work_dir, 'plot_%d_%d.dat' % (plot_no, i))
                self.tmp_files.append(dat_file)
                dat = open(dat_file, 'w')
                sub_total = 0
                for n in range(16):
                    angle = 90.0 - (n * 22.5)
                    sub_total += histograms[i][n]
                    if i > 0:
                        sub_total -= histograms[i-1][n]
                    if total > 0:
                        value = 100.0 * float(histograms[i][n]) / float(total)
                    else:
                        value = 0.0
                    if i == 0:
                        dat.write('%g %g\n' % (angle - 11.24, value * 0.994))
                    else:
                        dat.write('%g %g\n' % (angle - 8.1, 0))
                    dat.write('%g %g\n' % (angle - 8.0, value * 0.997))
                    dat.write('%g %g\n' % (angle, value))
                    dat.write('%g %g\n' % (angle + 8.0, value * 0.997))
                    if i == 0:
                        dat.write('%g %g\n' % (angle + 11.24, value * 0.994))
                        dat.write('%g %g\n' % (angle + 11.25, 0))
                    else:
                        dat.write('%g %g\n' % (angle + 8.1, 0))
                dat.close()
                # plot data
                if total > 0:
                    value = 100.0 * float(sub_total) / float(total)
                else:
                    value = 0.0
                if i == 0:
                    title = '0 .. %g (%.3g%%)' % (thresh[i], value)
                elif i == len(thresh) - 1:
                    title = '> %g (%.3g%%)' % (thresh[i-1], value)
                else:
                    title = '%g .. %g (%.3g%%)' % (thresh[i-1], thresh[i], value)
                result += '"%s" using 1:2 title "%s" with filledcurve lt %d' % (
                    dat_file, title, colour[i % len(colour)])
                if i > 0:
                    result += ', \\'
                result += '\n'
            return result

    def main(argv=None):
        if argv is None:
            argv = sys.argv
        try:
            opts, args = getopt.getopt(argv[1:], "h", ['help'])
        except getopt.error, msg:
            print >>sys.stderr, 'Error: %s\n' % msg
            print >>sys.stderr, __usage__.strip()
            return 1
        # process options
        for o, a in opts:
            if o == '-h' or o == '--help':
                print __usage__.strip()
                return 0
        # check arguments
        if len(args) != 4:
            print >>sys.stderr, 'Error: 4 arguments required\n'
            print >>sys.stderr, __usage__.strip()
            return 2
        params = DataStore.params(args[0])
        Localisation.SetApplicationLanguage(params)
        return RosePlotter(
            params,
            DataStore.calib_store(args[0]), DataStore.hourly_store(args[0]),
            DataStore.daily_store(args[0]), DataStore.monthly_store(args[0]),
            args[1]
            ).DoPlot(args[2], args[3])

    if __name__ == "__main__":
        sys.exit(main())

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