How to store selected attributes of vector layer using PyQGIS

Question

I'm following this PyQgis workshop: http://www.qgisworkshop.org/html/workshop/python_in_qgis_tutorial2.html#accessing-data-attributes

I have a point layer shapefile. I want to be able to retrieve and store x, y and name of each point( they already exist in attribute table and have indexes of 10, 11 and 1), hopefully in a dictionary format ((x,y) as key, name as value).

My problem starts here:

while provider.nextFeature(feat):
map = feat.attributeMap()  

I can't figure out how to use this 'map' dictionary. iterating through it I either get

"PyQt4.QtCore.QVariant object at 0x23C9C3B0" or "built-in method toString of QVariant object at 0x10D38D50".

any help is appreciated!

Answer 1

Use the toString() method on a QVariant object to get it's string value. There are a number of other methods (e.g. toInt(), toFloat(), toDouble() to name a few) for getting the value.

Here is an example:

>>> variant_string = QVariant('this is a string')
>>> variant_int = QVariant( 100)
>>> variant_string
<PyQt4.QtCore.QVariant object at 0x100f5abb0>
>>> variant_string.toString()
PyQt4.QtCore.QString(u'this is a string')
>>> str(variant_string.toString())
'this is a string'
>>> variant_int.toInt()
(100, True)

Notice that toInt() returns a tuple, the first element being the value and the second being a boolean indicating if the conversion to integer was successful.