#Example script: PLOT LVIS Level2 parameters vs Longitude for a selected sample in QGIS 
#http://lvis.gsfc.nasa.gov

#canvas = qgis.utils.iface.mapCanvas()
#registry = QgsMapLayerRegistry.instance()
#layers = registry.mapLayers()
#vectorLyr =  QgsVectorLayer('c:/temp/my_subset.shp','Layer 1', 'ogr)
#vectorLyr.isValid()
#layer = iface.addVectorLayer("c:/temp/my_subset.shp", "layer 1", "ogr")


import matplotlib.pyplot
import pylab
 
layer = qgis.utils.iface.activeLayer()
selection = layer.selectedFeatures()
print len(selection)
#initialize arrays
LON0 = []
ZG = []
RH25 = []
RH50 = []
RH75 = []
ZT = []
for feature in selection:
 attrs = feature.attributes()
 LON0.append(attrs[3])
 ZG.append(attrs[5])
 RH25.append(attrs[12]+attrs[5])
 RH50.append(attrs[17]+attrs[5])
 RH75.append(attrs[22]+attrs[5])
 ZT.append(attrs[8])

matplotlib.pyplot.scatter(LON0,ZG,color='r') 
matplotlib.pyplot.scatter(LON0,RH25,color='orange') 
matplotlib.pyplot.scatter(LON0,RH50,color='y')
matplotlib.pyplot.scatter(LON0,RH75,color='g')
matplotlib.pyplot.scatter(LON0,ZT,color='b')
matplotlib.pyplot.show()