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120 lines
4.1 KiB
Python
120 lines
4.1 KiB
Python
"""
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***************************************************************************
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VectorLayerHistogram.py
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---------------------
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Date : January 2013
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Copyright : (C) 2013 by Victor Olaya
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Email : volayaf at gmail dot com
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***************************************************************************
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* *
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* This program is free software; you can redistribute it and/or modify *
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* it under the terms of the GNU General Public License as published by *
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* the Free Software Foundation; either version 2 of the License, or *
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* (at your option) any later version. *
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* *
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***************************************************************************
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"""
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__author__ = "Victor Olaya"
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__date__ = "January 2013"
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__copyright__ = "(C) 2013, Victor Olaya"
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import warnings
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from qgis.core import (
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QgsProcessingException,
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QgsProcessingParameterFeatureSource,
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QgsProcessingParameterField,
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QgsProcessingParameterNumber,
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QgsProcessingParameterFileDestination,
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)
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from processing.algs.qgis.QgisAlgorithm import QgisAlgorithm
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from processing.tools import vector
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from qgis.PyQt.QtCore import QCoreApplication
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class VectorLayerHistogram(QgisAlgorithm):
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INPUT = "INPUT"
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OUTPUT = "OUTPUT"
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FIELD = "FIELD"
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BINS = "BINS"
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def group(self):
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return self.tr("Plots")
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def groupId(self):
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return "plots"
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def __init__(self):
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super().__init__()
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def initAlgorithm(self, config=None):
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self.addParameter(
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QgsProcessingParameterFeatureSource(self.INPUT, self.tr("Input layer"))
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)
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self.addParameter(
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QgsProcessingParameterField(
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self.FIELD,
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self.tr("Attribute"),
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parentLayerParameterName=self.INPUT,
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type=QgsProcessingParameterField.DataType.Numeric,
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)
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)
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self.addParameter(
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QgsProcessingParameterNumber(
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self.BINS, self.tr("number of bins"), minValue=2, defaultValue=10
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)
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)
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self.addParameter(
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QgsProcessingParameterFileDestination(
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self.OUTPUT, self.tr("Histogram"), self.tr("HTML files (*.html)")
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)
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)
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def name(self):
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return "vectorlayerhistogram"
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def displayName(self):
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return self.tr("Vector layer histogram")
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def shortDescription(self):
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return self.tr(
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"Generates a histogram with the values of the attribute of a vector layer."
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)
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def processAlgorithm(self, parameters, context, feedback):
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try:
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# importing plotly throws Python warnings from within the library - filter these out
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with warnings.catch_warnings():
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warnings.filterwarnings("ignore", category=ResourceWarning)
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warnings.filterwarnings("ignore", category=ImportWarning)
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import plotly as plt
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import plotly.graph_objs as go
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except ImportError:
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raise QgsProcessingException(
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QCoreApplication.translate(
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"VectorLayerHistogram",
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"This algorithm requires the Python “plotly” library. Please install this library and try again.",
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)
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)
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source = self.parameterAsSource(parameters, self.INPUT, context)
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if source is None:
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raise QgsProcessingException(
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self.invalidSourceError(parameters, self.INPUT)
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)
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fieldname = self.parameterAsString(parameters, self.FIELD, context)
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bins = self.parameterAsInt(parameters, self.BINS, context)
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output = self.parameterAsFileOutput(parameters, self.OUTPUT, context)
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values = vector.values(source, fieldname)
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data = [go.Histogram(x=values[fieldname], nbinsx=bins)]
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plt.offline.plot(data, filename=output, auto_open=False)
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return {self.OUTPUT: output}
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