numpy.seterrcall — NumPy v1.11 Manual (original) (raw)

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:	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.

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 + 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'}