英文:
Capturing a warning sent using logging.warning() from a library function, python
问题
我调用 Qsc 函数时，对于一些值，我收到以下警告：
logger.warning('Newton solve did not get close to desired tolerance. Final residual: {last_residual_norm}')
当发生这种情况时，我想捕获这个警告，以便我可以以不同的方式处理这些结果。
我希望解决这个问题而不改变库。
英文:
I call the Qsc function with various values, but for some values I receive the following warning:
Newton solve did not get close to desired tolerance. Final residual: 1.7380027083030736e-09
When this happens I want to capture the warning, so I can deal with these results differently.
I would like to solve the problem without changing the library.
This is the where the warning is sent from: logger.warning('Newton solve did not get close to desired tolerance. 'f'Final residual: {last_residual_norm}'), https://github.com/landreman/pyQSC/blob/1cb01ee6202144f3263150154164e72e74f7082c/qsc/newton.py#L59
I tried this:
import logging
import warnings
from qsc import Qsc
logging.captureWarnings(True)
with warnings.catch_warnings(record=True) as w:
stel = Qsc(rc=[1, 0.20990165844612937], zs=[0, -0.008780473233288922], nfp=2, etabar=-1.699682124042855)
warnings.warn("warn from warning")
logging.warn("warn from logging")
logging.warning("warning from logging")
if w:
for warning in w:
logging.warning(str(warning.message))
print("warning was captured\n")
And obtained this, meaning that I am only capturing the warning from warning.warn()
Newton solve did not get close to desired tolerance. Final residual: 1.7380027083030736e-09
WARNING:root:warning from logging
WARNING:root:warn from warning
warning was captured
答案1
得分: 1
你可能将WARNING级别的日志事件（通常使用记录器的warning方法发出）与warnings模块混淆了，后者是不同的东西。因此，你的catch_warnings()不会产生期望的效果。
要捕获警告：向记录器添加一个记录该消息的过滤器或发出该消息的处理程序，这将导致你想要的自定义处理，并从该过滤器中返回False。例如：
def newton_solution_fail_filter(record):
if not is_newton_failed_message(record): # 例如，通过检查record.msg
return True
custom_function_to_solve_the_problem() # 执行解决问题的操作
return False # 防止消息出现
logger_or_handler.addFilter(newton_solution_fail_filter)
英文:
You may be confusing a logging event at WARNING level (often emitted using the warning method of a logger) with the warnings module, which is a different thing. Hence, your catch_warnings() will not have the desired effect.
To capture the warning: Add a filter to the logger which logs that message or handler which emits the message, which leads to the custom processing you want, and return False from that filter. For example:
def newton_solution_fail_filter(record):
if not is_newton_failed_message(record): # e.g. by examing record.msg
return True
custom_function_to_solve_the_problem() # do your thing to solve it
return False # prevent the message appearing
logger_or_handler.addFilter(newton_solution_fail_filter)
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