# just the standard initialization
#
from qgis.core import QgsApplication, QgsFeature, QgsGeometry
from qgis.core import QgsMapLayerRegistry, QgsProject

from PyQt4.QtGui import QApplication
from PyQt4.QtCore import QFileInfo

app = QApplication([])
QgsApplication.setPrefixPath("/usr", True)
QgsApplication.initQgis()

project = QgsProject.instance()
project.read(QFileInfo('/home/mario/Documents/GIS/heliconiaBB.qgs'))

# import normal distribution from 'random'
#
from random import gauss

# all layers are in WGS 84, or I want the code to be independent from the
# layer coordinates reference system

# the points in my virtual reality
reality = QgsMapLayerRegistry.instance().mapLayersByName("points")[0]
# the points as measured by my virtual GPS machine, to be simulated here
gps_readings = QgsMapLayerRegistry.instance().mapLayersByName("gps")[0]

# the two layers have the same fields set, including 'code'
fields = reality.fields()

gps_readings.startEditing()
pr = gps_readings.dataProvider()

for feat in reality.getFeatures():
    dx = gauss(0.0, 3.0)
    dy = gauss(0.0, 3.0)

    # the following line is just pseudo-code
    fake_gps_reading = feat.geometry().asPoint() + (dx, dy)

    new_feat = QgsFeature(fields)
    new_feat['code'] = feat['code']
    new_feat.setGeometry(QgsGeometry.fromPoint(fake_gps_reading))
    pr.addFeatures( [ new_feat ] )

gps_readings.commitChanges()