hub_distance in python standalone script

Question

I need to load geometry from csv and then use it to calculate hub distance. I write the following script, but it doesn't work. What am I doing wrong?

 sys.path.append('/usr/share/qgis/python/plugins/')
 from processing.core.Processing import Processing
 from processing.tools import *
 qgs = QgsApplication([], True)

 QgsApplication.setPrefixPath("/usr", True)

 Processing.initialize()
 QgsApplication.initQgis()
 layer = QgsVectorLayer('from_excel.csv', 'from_excel', "delimitedtext")

 layer.setCrs(QgsCoordinateReferenceSystem(32365, QgsCoordinateReferenceSystem.EpsgCrsId))



layer2 = QgsVectorLayer('/home/raven/work/UpWork/Inputs/Cenefas.shp', 'Cenefas', 'ogr')
layer2.setCrs(QgsCoordinateReferenceSystem(32365, QgsCoordinateReferenceSystem.EpsgCrsId))

general.runalg("qgis:distancetonearesthub", layer, layer2, 'test', 0, 0, 'HubOutput')

QgsApplication.exitQgis()

Then I've bunch or errors:

1. Warning: Not all input layers use the same CRS.
2. Fields of width 255 truncated to 254 'NoneType' object has no attribute 'boundingBox'
3. Segmentation fault (core dumped)

Answer 1

I think there's a few issues:

1. I think you need to replace qgs = QgsApplication([], True) with qgs = QApplication([], True).

2. When loading a csv file, you need to set the relevant parameters such as the delimiter and (assuming you want to load it as a point layer) set the X Y fields. However, I found that calling this point layer into the algorithm fails as the path of the file also contains those settings. So perhaps it is best to import the csv as a layer and export this to a shapefile. Then call this shapefile into the algorithm.

3. I don't think EPSG:32365 exists, was this a typo?

---

The following code works for me using EPSG:27700 (note that I tested this on QGIS 2.18.2 for Windows 7 64-bit, you can adjust the paths accordingly):

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

sys.path.append('/usr/share/qgis/python/plugins/')
from processing.core.Processing import Processing
from processing.tools import *
Processing.initialize()

uri = '/home/raven/work/UpWork/Inputs/from_excel.csv?delimiter=,&crs=epsg:27700&xField=x&yField=y'
point_layer = QgsVectorLayer(uri, 'from_excel', 'delimitedtext')
point_path = '/home/raven/work/UpWork/Inputs/point.shp'
QgsVectorFileWriter.writeAsVectorFormat(point_layer, point_path, "utf-8", None, "ESRI Shapefile")

layer = QgsVectorLayer(point_path, 'point', 'ogr')

layer2 = QgsVectorLayer('/home/raven/work/UpWork/Inputs/Cenefas.shp', 'Cenefas', 'ogr')
layer2.setCrs(QgsCoordinateReferenceSystem(27700, QgsCoordinateReferenceSystem.EpsgCrsId))

general.runalg("qgis:distancetonearesthub", layer, layer2, 'test', 0, 0, 'HubOutput')

QgsApplication.exitQgis()
qgs.exit()