Python custom vision predictor fails

问题:

I'm using Python to retrieve a Blob image from Azure storage and then send it to Custom Vision for a prediction. This is the code:

import io
from azure.storage.blob import BlockBlobService
from azure.cognitiveservices.vision.customvision.prediction import CustomVisionPredictionClient



block_blob_service = BlockBlobService(
    account_name=account_name,
    account_key=account_key
)

fp = io.BytesIO()
block_blob_service.get_blob_to_stream(
    container_name, 
    blob_name, 
    fp, 
    max_connections=2
)

predictor = CustomVisionPredictionClient(
    cv_prediction_key, 
    endpoint=cv_endpoint
)

# This call breaks with the below error message
results = predictor.predict_image(
    cv_project_id,
    image_data.getvalue(),
    iteration_id=cv_iteration_id
)

However, executing the predict_image function results in the following error:

System.Private.CoreLib: Exception while executing function: Functions.ReloadPostgres. System.Private.CoreLib: Result: Failure
Exception: HttpOperationError: Operation returned an invalid status code 'Resource Not Found'
Stack:   File "~/.local/share/virtualenvs/py_func_app-GVYYSfCn/lib/python3.6/site-packages/azure/functions_worker/dispatcher.py", line 288, in _handle__invocation_request
    self.__run_sync_func, invocation_id, fi.func, args)
  File "~/.pyenv/versions/3.6.8/lib/python3.6/concurrent/futures/thread.py", line 56, in run
    result = self.fn(*self.args, **self.kwargs)
  File "~/.local/share/virtualenvs/py_func_app-GVYYSfCn/lib/python3.6/site-packages/azure/functions_worker/dispatcher.py", line 347, in __run_sync_func
    return func(**params)
  File "~/py_func_app/ReloadPostgres/__init__.py", line 14, in main
    data_handler.fetch_prediction_data()
  File "~/py_func_app/Shared_Code/data_handler.py", line 127, in fetch_prediction_data
    cv_handler.predict_image(image_data.getvalue(), cv_model)
  File "~/py_func_app/Shared_Code/custom_vision.py", line 30, in predict_image
    raise e
  File "~/py_func_app/Shared_Code/custom_vision.py", line 26, in predict_image
    iteration_id=cv_model.cv_iteration_id
  File "~/.local/share/virtualenvs/py_func_app-GVYYSfCn/lib/python3.6/site-packages/azure/cognitiveservices/vision/customvision/prediction/custom_vision_prediction_client.py", line 215, in predict_image
    raise HttpOperationError(self._deserialize, response)

回答1:

Here in below i am providing similar example using custom vision prediction using image URL, you can change it to image file :

# -*- coding: utf-8 -*-
"""
Created on Tue Mar 19 11:04:54 2019

@author: moverm
"""
#from azure.storage.blob import BlockBlobService
from azure.cognitiveservices.vision.customvision.prediction import CustomVisionPredictionClient


#block_blob_service = BlockBlobService(
#    account_name=account_name,
#    account_key=account_key
#)
#
#fp = io.BytesIO()
#block_blob_service.get_blob_to_stream(
#    container_name, 
#    blob_name, 
#    fp, 
#    max_connections=2
#)

predictor = CustomVisionPredictionClient(
    "prediction-key", 
    endpoint="https://southcentralus.api.cognitive.microsoft.com"
)
# This call breaks with the below error message
#results = predictor.predict_image(
#    'prediction-key',
#    image_data.getvalue(),
#    iteration_id=cv_iteration_id
#)
test_img_url = "https://pointsprizes-blog.s3-accelerate.amazonaws.com/316.jpg"
results = predictor.predict_image_url("project-Id", "Iteration-Id", url=test_img_url)

# Display the results.
for prediction in results.predictions:
    print ("\t" + prediction.tag_name + ": {0:.2f}%".format(prediction.probability * 100))

Basically issue is related to endpoint.Use https://southcentralus.api.cognitive.microsoft.com for an endpoint.

It should work, and you should be able to see the prediction probability.

Hope it helps.

---

回答2:

I tried to reproduce your issue and got a similar issue, which was caused by using the incorrect endpoint from Azure portal when I created a Cognitive Service on the region of Janpa East, as the figure below.

As the figure above shown, the endpoint is https://japaneast.api.cognitive.microsoft.com/customvision/training/v1.0 for version 1, but the azure-cognitiveservices-vision-customvision PyPI page points out the corrent endpoint which should be https://{AzureRegion}.api.cognitive.microsoft.com as the figure below.

So I got the similar issue with yours if using the incorrent endpoint, as below. My code used is the same as yours, the only difference is the running environment which yours is on Azure Functions, but mine is a console script.

Meanwhile, according to the source code custom_vision_prediction_client.py of Azure Cognitive Service SDK for Custom Vision, you can see the code base_url = '{Endpoint}/customvision/v2.0/Prediction' to concat your passed endpoint with /customvision/v2.0/Prediction to generate the real endpoint for calling prediction api.

Therefore, as @MohitVerma-MSFT said, using https://<your cognitive service region>.api.cognitive.microsoft.com for the current version of Python package.

Additional notes as below, there is an announce of important update for customvision.ai you need to know, it may make effect for your current code working soon after.