Import error with using QGIS Native functions in Jupyter Notebook environment

Question

I want to calculate area of all polygon features using Field Geometry function of QGIS 3.22 version. But somehow it always gives an import QGIS error, but when I tried to do a simple buffer of a vector layer in same Jupyter Notebook environment it worked.

import time
from qgis.core import (
    QgsApplication,
    QgsVectorLayer,
    QgsFields,
    QgsField,
    QgsFeature,
    QgsGeometry,
    QgsProject,
    QgsVectorFileWriter,
)
import processing

def calculate_area_with_qgis(vector_layer_path, output_layer_path):
    # Initialize QGIS application
    QgsApplication.setPrefixPath("C:/Program Files/QGIS 3.22.5/apps/gis-ltr/qgiscrashhandler.exe", True)
    os.environ['QGIS_PREFIX_PATH'] = 'C:/Program Files/QGIS 3.22.5'

    QgsApplication.initQgis()

    # Load the vector layer
    vector_layer = QgsVectorLayer(vector_layer_path, "vector_layer", "ogr")
    if not vector_layer.isValid():
        print("Failed to load the vector layer")
        return None

    # Set up the field calculator parameters
    parameters = {
        'INPUT': vector_layer,
        'FIELD_NAME': 'AREA',
        'FIELD_TYPE': 0,  # Double
        'FIELD_LENGTH': 10,
        'FIELD_PRECISION': 3,
        'FORMULA': '$area',
        'OUTPUT': output_layer_path
    }

    # Run the field calculator algorithm
    start_time = time.time()
    processing.run("native:fieldcalculator", parameters)
    end_time = time.time()
    elapsed_time = end_time - start_time

    # Exit QGIS application
    QgsApplication.exitQgis()

    return elapsed_time

vector_layer_path = r"C:/Users/schakraborty/OneDrive - RMS/Desktop/INDUSTRIES/South Africa/Provinces/Kwaza_u_natul/Output/try_xyz/kwaza_natul_merged.shp"
output_layer_path = r"C:/Users/schakraborty/OneDrive - RMS/Desktop/INDUSTRIES/South Africa/Provinces/Kwaza_u_natul/Output/try_xyz/kwaza_natul_merged_area.shp"

elapsed_time = calculate_area_with_qgis(vector_layer_path, output_layer_path)
print(f"Elapsed time: {elapsed_time} seconds")

The error is coming as this -

ImportError Traceback (most recent call last)
Cell In[4], line 12
      1 import time
      2 from qgis.core import (
      3     QgsApplication,
      4     QgsVectorLayer,
   (...)
     10     QgsVectorFileWriter,
     11 )
---> 12 import processing
     14 def calculate_area_with_qgis(vector_layer_path, output_layer_path):
     15     # Initialize QGIS application
     16     QgsApplication.setPrefixPath("C:/Program Files/QGIS 3.22.5/apps/gis-ltr/qgiscrashhandler.exe", True)

File ~\AppData\Local\anaconda3\envs\testing1\Library\python\qgis\utils.py:888, in _import(name, globals, locals, fromlist, level)
    884                     _RemoveDllDirectory(_import_paths.pop(p))
    886             _import_path = new_path
--> 888 mod = _builtin_import(name, globals, locals, fromlist, level)
    890 if mod and getattr(mod, '__file__', None):
    891     module_name = mod.__name__ if fromlist else name


File ~\AppData\Local\anaconda3\envs\testing1\Library\python\qgis\analysis\__init__.py:26
     22 __copyright__ = '(C) 2014, Nathan Woodrow'
     24 from qgis.PyQt import QtCore
---> 26 from qgis._analysis import *
     28 # preserve API compatibility following QgsExifTools moved to core
     29 from qgis.core import QgsExifTools

File ~\AppData\Local\anaconda3\envs\testing1\Library\python\qgis\utils.py:888, in _import(name, globals, locals, fromlist, level)
    884                     _RemoveDllDirectory(_import_paths.pop(p))
    886             _import_path = new_path
--> 888 mod = _builtin_import(name, globals, locals, fromlist, level)
    890 if mod and getattr(mod, '__file__', None):
    891     module_name = mod.__name__ if fromlist else name

ImportError: DLL load failed while importing _analysis: The specified module could not be found.

Answer 1

Since I couldn't format well in a comment:

This is partial answer in terms of going from processing functions not available to being available. Including an example use.

What functions to call was taken from test_qgsprocessinginplace.py

Ubuntu Linux so adjust prefix path as needed.

    import qgis.core as core
    core.QgsApplication.setPrefixPath("/usr", True)
    qgs = core.QgsApplication([], False)
    qgs.initQgis()
    register = core.QgsApplication.processingRegistry()
    print(len(register.algorithms()))
    from qgis.analysis import QgsNativeAlgorithms
    core.QgsApplication.processingRegistry().addProvider(QgsNativeAlgorithms())
    print(len(register.algorithms()))
    algorithm_subset = [alg for alg in register.algorithms() if 'fieldcalculator' in alg.name()]
    print(len(algorithm_subset))
    if len(algorithm_subset) == 1:
       algorithm_subset[0].run
    alg = register.createAlgorithmById('native:creategrid')
    argz = {'TYPE':0,'EXTENT':'539540,540123,5446000,5446600 [EPSG:26900]',
        'HSPACING':250,'SPACING':500,'HOVERLAY':0,'VOVERLAY':0,
        'CRS':core.QgsCoordinateReferenceSystem('EPSG:26909'),'OUTPUT':'TEMPORARY_OUTPUT'}
    context = core.QgsProcessingContext()
    invalid_geometry_policy=core.QgsFeatureRequest.GeometryNoCheck
    context.setInvalidGeometryCheck(invalid_geometry_policy)
    context.setProject(core.QgsProject.instance())
    alg.asPythonCommand(argz, context)
    qgs.exitQgis()

I get number of algorithms going from zero to 238.

Addressing the exception reported in the question

If import processing is used outside of qgis I get import error

In qgis python console: processing <module 'processing' from '/usr/share/qgis/python/plugins/processing/init.py'>

So can't use import processing in the script.