Ошибка при выполнении сценария python qgis

Ошибка при выполнении сценария Python:

TypeError: ‘float’ object is not subscriptable
Traceback (most recent call last):
File «C:/Users/Dorogokuplya/AppData/Roaming/QGIS/QGIS3profilesdefault/python/pluginsqgis2webmaindialog.py», line 350, in saveMap
feedback=self.feedback)
File «C:/Users/Dorogokuplya/AppData/Roaming/QGIS/QGIS3profilesdefault/python/pluginsqgis2webmapboxWriter.py», line 104, in write
folder=dest_folder)
File «C:/Users/Dorogokuplya/AppData/Roaming/QGIS/QGIS3profilesdefault/python/pluginsqgis2webmapboxWriter.py», line 294, in writeMapbox
useOSMB, vtSources, layers)
File «C:/Users/Dorogokuplya/AppData/Roaming/QGIS/QGIS3profilesdefault/python/pluginsqgis2webmapboxLayerScripts.py», line 145, in writeVectorLayer
mblayers = getLayerStyle(layer)
File «C:/Users/Dorogokuplya/AppData/Roaming/QGIS/QGIS3profilesdefault/python/pluginsqgis2webmapboxStyleScripts.py», line 43, in getLayerStyle
mapboxStyle = bridgestyle.qgis.layerStyleAsMapbox(layer)
File «C:UsersDorogokuplyaAppDataRoamingQGISQGIS3profilesdefaultpythonpluginsgdrive_providerextlibsbridgestyleqgis_init_.py», line 41, in layerStyleAsMapbox
mbox, mbWarnings = mapboxgl.fromgeostyler.convert(geostyler)
File «C:UsersDorogokuplyaAppDataRoamingQGISQGIS3profilesdefaultpythonpluginsgdrive_providerextlibsbridgestylemapboxglfromgeostyler.py», line 10, in convert
layers = processLayer(geostyler)
File «C:UsersDorogokuplyaAppDataRoamingQGISQGIS3profilesdefaultpythonpluginsgdrive_providerextlibsbridgestylemapboxglfromgeostyler.py», line 31, in processLayer
layers = processRule(rule, layer[«name»])
File «C:UsersDorogokuplyaAppDataRoamingQGISQGIS3profilesdefaultpythonpluginsgdrive_providerextlibsbridgestylemapboxglfromgeostyler.py», line 47, in processRule
layers = [processSymbolizer(s) for s in rule[«symbolizers»]]
File «C:UsersDorogokuplyaAppDataRoamingQGISQGIS3profilesdefaultpythonpluginsgdrive_providerextlibsbridgestylemapboxglfromgeostyler.py», line 47, in
layers = [processSymbolizer(s) for s in rule[«symbolizers»]]
File «C:UsersDorogokuplyaAppDataRoamingQGISQGIS3profilesdefaultpythonpluginsgdrive_providerextlibsbridgestylemapboxglfromgeostyler.py», line 126, in processSymbolizer
symbolizer = _textSymbolizer(sl)
File «C:UsersDorogokuplyaAppDataRoamingQGISQGIS3profilesdefaultpythonpluginsgdrive_providerextlibsbridgestylemapboxglfromgeostyler.py», line 151, in _textSymbolizer
offsetx = convertExpression(offset[0])
TypeError: ‘float’ object is not subscriptable

Версия Python: 3.7.0 (v3.7.0:1bf9cc5093, Jun 27 2018, 04:59:51) [MSC v.1914 64 bit (AMD64)]
Версия: 3.6.3-Noosa Noosa, 0c5774c068

Расположение Python:
C:/Users/Dorogokuplya/AppData/Roaming/QGIS/QGIS3profilesdefault/python/pluginsindoor_schematic
C:/PROGRA1/QGIS31.6/apps/qgis/./python
C:/Users/Dorogokuplya/AppData/Roaming/QGIS/QGIS3profilesdefault/python
C:/Users/Dorogokuplya/AppData/Roaming/QGIS/QGIS3profilesdefault/python/plugins
C:/PROGRA1/QGIS31.6/apps/qgis/./python/plugins
C:Program FilesQGIS 3.6binpython37.zip
C:PROGRA1QGIS31.6appsPython37DLLs
C:PROGRA1QGIS31.6appsPython37lib
C:Program FilesQGIS 3.6bin
C:PROGRA1QGIS31.6appsPython37
C:PROGRA1QGIS31.6appsPython37libsite-packages
C:PROGRA1QGIS31.6appsPython37libsite-packageswin32
C:PROGRA1QGIS31.6appsPython37libsite-packageswin32lib
C:PROGRA1QGIS31.6appsPython37libsite-packagesPythonwin
C:/Users/Dorogokuplya/AppData/Roaming/QGIS/QGIS3profilesdefault/python
C:/Users/Dorogokuplya/AppData/Roaming/QGIS/QGIS3profilesdefault/python/pluginsgdrive_provider
C:UsersDorogokuplyaAppDataRoamingQGISQGIS3profilesdefaultpythonpluginsgdrive_providerextlibs
C:/Users/Dorogokuplya/AppData/Roaming/QGIS/QGIS3profilesdefault/python/pluginsqgis2web
C:UsersDorogokuplyaAppDataRoamingQGISQGIS3profilesdefaultpythonplugins
C:/Gis

I was fortunate enough to get in touch with the author of the book so I will share his response here:

I suspect I may know what the problem is…after looking at this
reader’s problems in more depth, I’ve discovered that something has
changed in newer versions of QGIS, and the example code no longer
works as it is written. In technical terms, it seems that you now
need to instantiate the QApplication object before making the call to
QgsApplication.initQgis() — the example program in the book
instantiates the QApplication object after calling
QgsApplication.initQgis(), which causes the program to crash. To fix
this, change the main() function to look like the following:

def main():
    """  Our main program.
    """
    app = QApplication(sys.argv)
    QgsApplication.setPrefixPath(os.environ['QGIS_PREFIX'],True)
    QgsApplication.initQgis()

    viewer = MapViewer("C:/folder/shapefile.shp")
    viewer.show()

    app.exec_()

    QgsApplication.exitQgis()

As you can see, I’ve moved the «app = QApplication(sys.argv)» line to the top.

Important Note: Make sure that forward slashes are used in viewer = MapViewer("C:/folder/shapefile.shp") — using a backslash will result in an error message stating that the shapefile is invalid.

I also thought it would be worth mentioning that none of the above fixes (comments on the question) were necessary. So, the script will work if the paths are defined as follows:

SET OSGEO4W_ROOT=C:OSGeo4W64
SET QGIS_PREFIX=%OSGEO4W_ROOT%appsqgis
SET PATH=%PATH%;%QGIS_PREFIX%bin
SET PYTHONPATH=%QGIS_PREFIX%python;%PYTHONPATH%

Then, the entire script looks like this:

import sys
import os
from qgis.core import *
from qgis.gui import *
from PyQt4.QtGui import *
from PyQt4.QtCore import Qt



#############################################################################


class MapViewer(QMainWindow):
    def __init__(self, shapefile):
        QMainWindow.__init__(self)
        self.setWindowTitle("Map Viewer")

        canvas = QgsMapCanvas()
        canvas.useImageToRender(False)
        canvas.setCanvasColor(Qt.white)
        canvas.show()

        layer = QgsVectorLayer(shapefile, "layer1", "ogr")
        if not layer.isValid():
            raise IOError("Invalid shapefile")

        QgsMapLayerRegistry.instance().addMapLayer(layer)
        canvas.setExtent(layer.extent())
        canvas.setLayerSet([QgsMapCanvasLayer(layer)])

        layout = QVBoxLayout()
        layout.addWidget(canvas)

        contents = QWidget()
        contents.setLayout(layout)
        self.setCentralWidget(contents)

#############################################################################


def main():
    """  Our main program.
    """
    app = QApplication(sys.argv)
    QgsApplication.setPrefixPath(os.environ['QGIS_PREFIX'],True)
    QgsApplication.initQgis()

    viewer = MapViewer("C:/folder/shapefile.shp")
    viewer.show()

    app.exec_()

    QgsApplication.exitQgis()

#############################################################################

if __name__ == "__main__":
    main()

Execute it in the OSGEO4W Shell using the following command:

python "C:script.py"

Lastly, note that at the time of this writing, the script works properly and launches a viewer showing the shapefile referenced, but returns a few errors in the shell that do not seem to be problematic:

ERROR: Opening of authentication db FAILED
ERROR: Unable to establish authentication database connection
ERROR: Auth db could not be created and opened
QSqlDatabasePrivate::database: unable to open database: "unable to open database file Error opening database"
ERROR: Opening of authentication db FAILED

Much thanks to the author Erik Westra for providing me with this solution.