[GIS] Writing vector layer to CSV file with geometry using PyQGIS

csvfields-attributesgeometrypyqgis

I use Python try to write vector layer file to csv file with this code:

QgsVectorFileWriter.writeAsVectorFormat(mylayer, r'c:\temp\xyz.csv', "utf-8", None, "CSV")

It can export to xyz.csv but only attributes show in the csv, not the geometry column.

How can I export both attribute and spatial data into csv file?

Best Answer

A similar answer was provided from this post:

Save as .csv with coordinates in both QGIS 2.2 and PyqGIS

Just add layerOptions ='GEOMETRY=AS_XYZ at the end:

layer = QgsVectorLayer("path/to/shapefile", "name", "ogr")
QgsVectorFileWriter.writeAsVectorFormat(layer, r'c:\temp\xyz.csv', "utf-8", None, "CSV", layerOptions='GEOMETRY=AS_XYZ')

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[GIS] Error while importing CSV File using PyQGIS

It's having problems with the letter s, because your code specifies that as a delimiter (delimiter=%ss is getting interpreted as "," and "s"). Try delimiter=%s.

[GIS] CSV to Geodataframe : How to have valid geometry objects

You probably have invalid geometries in your dataset, to find the invalid geometries you can either load your csv to qgis and run Vector -> Geometry Tools -> Check validity

or loop through your dataframe to find the invalid geometries:

for index, row in csv_gdf.iterrows():
    geom = row['geometry']
    if len(geom.coords) <= 2:
          print "This row has an invalid polygon geometry"
          # this is just one example of invalid geometries, there are also overlapping vertices, ...

I would recommend you the first check even if qgis is not tagged in your question

EDIT: generating the geometry as a shapely.geometry object

from shapely.wkt import loads

# either all at once :
csv_gdf['geometry'] = csv_gdf['geometry'].apply(loads))

# or one by one to detect possible geometry errors
for index, row in csv_gdf.iterrows():
    # it will throw an error where the geometry WKT isn't valid
    # csv_gdf.set_value(index, 'geometry', loads(row['geometry'])) --> deprecated
    csv_gdf.loc[index, 'geometry'] = loads(row['geometry'])

Best Answer

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[GIS] Error while importing CSV File using PyQGIS

[GIS] CSV to Geodataframe : How to have valid geometry objects

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