[Qgis-developer] PyQGIS Cookbook, MySQL geometries and Graduated symbol renderer

[Germán Carrillo]

Hi Martin,

I would like to propose a couple of Python snippets to be included in the
PyQGIS Cookbook.

1)  Load of MySQL geometries:
----------------------
uri =
"MySQL:dbname,host=localhost,port=3306,user=root,password=xxx|layername=my_table"
vLayer = QgsVectorLayer( uri, 'my_table', 'ogr' )
----------------------
BTW, I'm not sure if it is the best way to do it, but it works.

2) Graduated symbol renderer (Old symbology):
----------------------
fieldName = "My_Field"
numberOfClasses = 5
mFieldMap = {}

# Get the field index based on the field name
fields = layer.pendingFields()
for ( key, field ) in fields.iteritems():
    if field.type() == QVariant.Int or field.type() == QVariant.Double:

        mFieldMap[ str( field.name() ) ] = key
fieldIndex = mFieldMap[ fieldName ]

# Create the renderer object
renderer = QgsGraduatedSymbolRenderer( layer.geometryType() )
renderer.setMode( QgsGraduatedSymbolRenderer.EqualInterval ) #
EqualInterval/Quantile/Empty

# Prepare the required symbol objects
symbolList = []
geom = layer.geometryType()
provider = layer.dataProvider()
for i in range( numberOfClasses ):
    symbol = QgsSymbol( geom )
    brush = QBrush()
    brush.setColor( self.randomColor() )
    brush.setStyle( Qt.SolidPattern )
    symbol.setBrush( brush )
    symbolList.append( symbol )

# Define classes
minimum = provider.minimumValue( fieldIndex ).toDouble()[ 0 ]
maximum = provider.maximumValue( fieldIndex ).toDouble()[ 0 ]
for i in range( numberOfClasses ):
    # Switch if attribute is int or double
    lower = ('%.*f' % (2, minimum + ( maximum - minimum ) / numberOfClasses
* i ) )
    upper = ('%.*f' % (2, minimum + ( maximum - minimum ) / numberOfClasses
* ( i + 1 ) ) )

    lowerString = QVariant( lower ).toString()
    upperString = QVariant( upper ).toString()
    symbolList[ i ].setLowerValue( lowerString )
    symbolList[ i ].setUpperValue( upperString )
    symbolList[ i ].setLabel( lowerString + " - " + upperString )

# Define a symbol object based on each class
for i in range( numberOfClasses ):
    symbol = symbolList[ i ]
    lower_bound = symbol.lowerValue()
    upper_bound = symbol.upperValue()
    label = symbol.label()

    sy = QgsSymbol( layer.geometryType(), lower_bound, upper_bound, label )
    sy.setFillColor( symbol.brush().color() )
    sy.setFillStyle( symbol.brush().style() )

    renderer.addSymbol( sy )

renderer.setClassificationField( fieldIndex )
layer.setRenderer( renderer )
----------------------


Regards,

Germán

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