numpy.seterrcall()

numpy.seterrcall(func) [source]

Set the floating-point error callback function or log object.

There are two ways to capture floating-point error messages. The first is to set the error-handler to ?call?, using seterr. Then, set the function to call using this function.

The second is to set the error-handler to ?log?, using seterr. Floating-point errors then trigger a call to the ?write? method of the provided object.

Parameters:

Parameters:	func : callable f(err, flag) or object with write method Function to call upon floating-point errors (?call?-mode) or object whose ?write? method is used to log such message (?log?-mode). The call function takes two arguments. The first is a string describing the type of error (such as ?divide by zero?, ?overflow?, ?underflow?, or ?invalid value?), and the second is the status flag. The flag is a byte, whose four least-significant bits indicate the type of error, one of ?divide?, ?over?, ?under?, ?invalid?: [0 0 0 0 divide over under invalid] In other words, `flags = divide + 2over + 4under + 8*invalid`. If an object is provided, its write method should take one argument, a string.
Returns:	h : callable, log instance or None The old error handler.

func : callable f(err, flag) or object with write method

Function to call upon floating-point errors (?call?-mode) or object whose ?write? method is used to log such message (?log?-mode).

The call function takes two arguments. The first is a string describing the type of error (such as ?divide by zero?, ?overflow?, ?underflow?, or ?invalid value?), and the second is the status flag. The flag is a byte, whose four least-significant bits indicate the type of error, one of ?divide?, ?over?, ?under?, ?invalid?:

[0 0 0 0 divide over under invalid]

In other words, flags = divide + 2*over + 4*under + 8*invalid.

If an object is provided, its write method should take one argument, a string.

Returns:

h : callable, log instance or None

The old error handler.

Examples

Callback upon error:

>>> def err_handler(type, flag):
...     print("Floating point error (%s), with flag %s" % (type, flag))
...

>>> saved_handler = np.seterrcall(err_handler)
>>> save_err = np.seterr(all='call')

>>> np.array([1, 2, 3]) / 0.0
Floating point error (divide by zero), with flag 1
array([ Inf,  Inf,  Inf])

>>> np.seterrcall(saved_handler)
<function err_handler at 0x...>
>>> np.seterr(**save_err)
{'over': 'call', 'divide': 'call', 'invalid': 'call', 'under': 'call'}

Log error message:

>>> class Log(object):
...     def write(self, msg):
...         print("LOG: %s" % msg)
...

>>> log = Log()
>>> saved_handler = np.seterrcall(log)
>>> save_err = np.seterr(all='log')

>>> np.array([1, 2, 3]) / 0.0
LOG: Warning: divide by zero encountered in divide

array([ Inf,  Inf,  Inf])

>>> np.seterrcall(saved_handler)
<__main__.Log object at 0x...>
>>> np.seterr(**save_err)
{'over': 'log', 'divide': 'log', 'invalid': 'log', 'under': 'log'}

Links:

https://docs.scipy.org/doc/numpy-1.11.0/reference/generated/numpy.seterrcall.html

doc_NumPy

2017-01-10 18:18:39

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