1. import sys
2. from qgis.utils import iface
3. from qgis.core import *
4. from PyQt4 import QtGui
5. from PyQt4 import QtCore
6.  
7. FILES_FOLDER_PATH = "C:/Users/PawelW/Desktop/lab3/"
8.  
9. def main():
10.     exercise_1()
11.     exercise_2()
12.  
13. def exercise_1():
14.     clear()
15.     world_layer = load_layer('WORLD_RG/WORLD_RG_10M_2010.shp', "World")
16.     province_layer = load_layer('POL_adm/POL_adm1.shp', 'Province')
17.     country_layer = load_layer('POL_adm/POL_adm2.shp', 'Country')
18.     set_color(world_layer, 15, 163, 42)
19.     set_color(province_layer, 13, 76, 212)
20.     set_color(country_layer, 232, 5, 5)
21.     set_transparency(country_layer, 0.8)
22.     province_layer.selectAll()
23.     iface.mapCanvas().zoomToSelected(province_layer)
24.  
25. def exercise_2():
26.     clear()
27.     province_layer = load_layer('POL_adm/POL_adm1.shp', 'Province')
28.     provinces_list = get_provinces_list(province_layer)
29.     del_area(province_layer)
30.     areas_sizes_list = calculate_areas_size(province_layer)
31.     save_to_file(provinces_list, areas_sizes_list)
32.  
33. def error(info):
34.     print >> sys.stderr, "Error:", info
35.  
36. def load_layer(sub_path, name):
37.     layer = QgsVectorLayer(FILES_FOLDER_PATH + sub_path, name, "ogr")
38.     if not layer.isValid(): error("Layer :" + sub_path + " failed to load!")
39.     QgsMapLayerRegistry.instance().addMapLayer(layer)
40.     layer.setCacheImage(None)
41.     layer.triggerRepaint()
42.     return layer
43.  
44. def clear():
45.     for item in QgsMapLayerRegistry.instance().mapLayers().items():
46.         layer_id = item[1].id()
47.         QgsMapLayerRegistry.instance().removeMapLayer(layer_id)
48.        
49. def set_color(layer, r=0, g=0, b=0):
50.     if r<0.0: r=0
51.     if r>255.0: r=255
52.     if g<0.0: g=0
53.     if g>255.0: g=255
54.     if b<0.0: b=0
55.     if b>255.0: b=255
56.     myRenderer = layer.rendererV2()
57.     mySymbol = myRenderer.symbol()
58.     mySymbol.setColor(QtGui.QColor(r,g,b))
59.     layer.setCacheImage(None)
60.     layer.triggerRepaint()
61.     iface.mapCanvas().refresh()
62.  
63. def set_transparency(layer, tval=0.5):
64.     if tval<0.0: tval=0
65.     if tval>1.0: tval=1
66.     tval = 1.0 - tval
67.     myRenderer = layer.rendererV2()
68.     mySymbol = myRenderer.symbol()
69.     mySymbol.setAlpha(tval)
70.     layer.setCacheImage(None)
71.     layer.triggerRepaint()
72.     iface.mapCanvas().refresh()
73.  
74. def get_provinces_list(layer):
75.     provinces_list = []
76.     provider = layer.dataProvider()
77.     feature_list = provider.getFeatures()
78.     feat = QgsFeature()
79.     while feature_list.nextFeature(feat):
80.         attrs = feat.attributes()
81.         provinces_list.append(attrs[6].encode('utf-8'))
82.     return provinces_list
83.  
84. def del_area(layer, nr=9):
85.     if not layer.isEditable():
86.         layer.startEditing()
87.     res = layer.deleteAttribute( nr )
88.     layer.commitChanges()
89.  
90. def calculate_areas_size(layer):
91.     areas_list = []
92.     if not layer.isEditable():
93.         layer.startEditing()
94.     lProvider = layer.dataProvider()
95.     lProvider.addAttributes([QgsField('AREA', QtCore.QVariant.Double)])
96.     layer.commitChanges()
97.     layer.startEditing()
98.     for feature in layer.getFeatures():
99.         calculator = QgsDistanceArea()
100.         calculator.computeAreaInit()
101.         geometry = feature.geometry()
102.         sum_area = 0
103.         if not geometry.isMultipart():
104.             polygon = geometry.asPolygon()
105.             if len(polygon) > 0:
106.                 degrees = calculator.measurePolygon(polygon[0])
107.                 area = calculator.convertMeasurement(degrees, QGis.Degrees, QGis.Meters, True)
108.                 sum_area += area[0]
109.         else:
110.             multi_polygon = geometry.asMultiPolygon()
111.             for sub_polygon in multi_polygon:
112.                 degrees = calculator.measurePolygon(sub_polygon[0])
113.                 area = calculator.convertMeasurement(degrees, QGis.Degrees, QGis.Meters, True)
114.                 sum_area += area[0]
115.         layer.changeAttributeValue(len(areas_list), 9, sum_area)
116.         areas_list.append(sum_area)
117.     layer.commitChanges()
118.     return areas_list
119.  
120. def save_to_file(names, areas):
121.     result = open(FILES_FOLDER_PATH + 'result.txt', "w+")
122.     result.write("Numer            Nazwa         Powierzchnia  \n")
123.  
124.     for i in range(len(names)):
125.         result.write(str(i+1) + ".  " + names[i] + "   " + str(areas[i]/1000000) + " km kwadratowych\n")
126.     result.close()
127.  
128. if __name__ == '__main__':
129.     main()
130.  
131.