for 循环中的错误/异常处理 - python

Question

我正在使用 Google Cloud NL API 来分析一些描述的情绪。至于某些行，错误 InvalidArgument: 400 The language vi is not supported for document_sentiment analysis. 不断弹出，我想围绕它构建一种方法，而不是拼命地试图找到发生这种情况的原因并删除负责的行。不幸的是，我是 Python 的新手，不确定如何正确操作。

我的代码如下：

description_list = []
sentimentscore_list=[]
magnitude_list=[]

# Create a Language client
language_client = google.cloud.language.LanguageServiceClient()


for i in range(len(description)):      # use the translated description if the original description is not in English
    if description_trans[i] == '':
        descr = description[i]
    else:
        descr = description_trans[i]


    document = google.cloud.language.types.Document(
        content=descr,
        type=google.cloud.language.enums.Document.Type.PLAIN_TEXT)

    # Use Language to detect the sentiment of the text.
    response = language_client.analyze_sentiment(document=document)
    sentiment = response.document_sentiment
    sentimentscore_list.append(sentiment.score)
    magnitude_list.append(sentiment.magnitude)
    # Add the description that was actually used to the description list
    description_list.append(descr)

谁能向我解释如何将这个 for 循环（或者可能后一部分就足够了）包装到 error/exception 处理中，以便它只是 "skips over" 它不能阅读并继续下一篇？此外，我希望仅在实际分析描述时才附加 'description_list'（而不是在它卡在错误处理中时）。

非常感谢任何帮助！！谢谢:)

编辑：有人要求我提供更完整的错误回溯：

回溯（最近调用最后）：

  File "<ipython-input-64-6e3db1d976c9>", line 1, in <module>
    runfile('/Users/repos/NLPAnalysis/GoogleTest.py', wdir='/Users/repos/NLPAnalysis')

  File "/Users/anaconda3/lib/python3.6/site-packages/spyder/utils/site/sitecustomize.py", line 710, in runfile
    execfile(filename, namespace)

  File "/Users/anaconda3/lib/python3.6/site-packages/spyder/utils/site/sitecustomize.py", line 101, in execfile
    exec(compile(f.read(), filename, 'exec'), namespace)

  File "/Users/repos/NLPAnalysis/GoogleTest.py", line 45, in <module>
    response = language_client.analyze_sentiment(document=document)

  File "/Users/anaconda3/lib/python3.6/site-packages/google/cloud/language_v1/gapic/language_service_client.py", line 180, in analyze_sentiment
    return self._analyze_sentiment(request, retry=retry, timeout=timeout)

  File "/Users/anaconda3/lib/python3.6/site-packages/google/api_core/gapic_v1/method.py", line 139, in __call__
    return wrapped_func(*args, **kwargs)

  File "/Users/anaconda3/lib/python3.6/site-packages/google/api_core/retry.py", line 260, in retry_wrapped_func
    on_error=on_error,

  File "/Users/anaconda3/lib/python3.6/site-packages/google/api_core/retry.py", line 177, in retry_target
    return target()

  File "/Users/anaconda3/lib/python3.6/site-packages/google/api_core/timeout.py", line 206, in func_with_timeout
    return func(*args, **kwargs)

  File "/Users/anaconda3/lib/python3.6/site-packages/google/api_core/grpc_helpers.py", line 56, in error_remapped_callable
    six.raise_from(exceptions.from_grpc_error(exc), exc)

  File "<string>", line 3, in raise_from

InvalidArgument: 400 The language vi is not supported for document_sentiment analysis.

Answer 1

在回溯中，查看第四行，这是您代码中导致异常的同一行。我们总是将 try except 放在我们认为会导致异常的代码块周围。其他所有东西都放在块外面。

try:
    response = language_client.analyze_sentiment(document=document)
except InvalidArgument:
    continue
# Assuming none of these would work if we don't get response?
description_list.append(descr)
sentiment = response.document_sentiment
entimentscore_list.append(sentiment.score)
magnitude_list.append(sentiment.magnitude)
# Add the description that was actually used to the description list

我们尝试从语言客户端获得响应，它引发了一个异常说InvalidArgument，我们抓住了。现在我们知道我们不需要做任何事情，我们使用 continue，然后继续下一次迭代。

您可能需要像 -

一样导入 InvalidArgument

from google.api_core.exceptions import InvalidArgument

在代码中使用它之前。

关于继续，你是对的。更多关于 continue statement and how to handle exceptions in python.

Answer 2

我同意 ThatBird 的观点，即在 try 块中包装太多代码会使调试内部错误变得复杂。我建议使用 python 的 continue 关键字。

try:
    # smallest block of code you foresee an error in
    response = language_client.analyze_sentiment(document=document) # I think your exception is being raised in this call
except InvalidArgument as e:
    # your trace shows InvalidArgument being raised and it appears you dont care about it
    continue # continue to next iteration since this error is expected
except SomeOtherOkayException as e:
    # this is an example exception that is also OK and "skippable"
    continue # continue to next iteration
except Exception as e:
    # all other exceptions are BAD and unexpected.This is a larger problem than just this loop
    raise e # break the looping and raise to calling function

sentiment = response.document_sentiment
sentimentscore_list.append(sentiment.score)
magnitude_list.append(sentiment.magnitude)
# Add the description that was actually used to the description list
description_list.append(descr)
# more code here...

本质上，您是在明确捕获预期的异常，并在出现异常时丢弃该迭代并继续下一个迭代。您应该提出所有其他意外情况。

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