Ufunc generates unintuitive AttributeError on object arrays (Trac #1013)

[thouis]

Original ticket http://projects.scipy.org/numpy/ticket/1013 on 2009-02-20 by @wesm, assigned to unknown.

This error is very unintuitive for end-users, arrays formed from SQL query results can frequently end up as object arrays by accident.

In [15]: arr = np.random.randn(100).astype(object)

In [16]: np.log(arr)

AttributeError Traceback (most recent call last)

H:\workspace\Python\src in ()

AttributeError: log

Same AttributeError is raised for other ufuncs

[thouis]

@rkern wrote on 2009-02-20

Can you suggest an error message text that you would have been more helpful?

[thouis]

Milestone changed to Unscheduled by @mwiebe on 2011-03-24

[thouis]

Title changed from Ufunc generates AttributeError on object arrays to Ufunc generates unintuitive AttributeError on object arrays by @mwiebe on 2011-03-24

[hayd]

Confusing error in action: http://stackoverflow.com/questions/16968433/error-when-trying-to-apply-log-method-to-pandas-data-frame-column-in-python

[hayd]

Perhaps a better error message is:

TypeError("%s requires an array with numeric dtype but was passed %s" % ufunc, x.dtype)

(I think it should TypeError rather than an AttributeError...?)

When passing an array of strings to numpy.log you get:

TypeError: Not implemented for this type

I think this would also be improved with the above - more descriptive - message.

[njsmith]

The reason for the AttributeError is that as a last ditch attempt, np.log
and friends on an object array will try doing obj.log(), and it's this last
ditch attempt that's failing.

I agree the message is tremendously confusing though and it's bitten me
several times. If you want to submit a pull request then many people would
be grateful.
On 6 Jun 2013 20:53, "Andy Hayden" notifications@github.com wrote:

Perhaps a better error message is:

TypeError("%s requires an array with numeric dtype but was passed %s" % ufunc, x.dtype)

(I think it should TypeError rather than an AttributeError...?)

When passing an array of strings to numpy.log you get:

TypeError: Not implemented for this type

I think this would also be improved with the above - more descriptive -
message.

—
Reply to this email directly or view it on GitHubhttps://github.com//issues/1611#issuecomment-19069832
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[hayd]

Will have a look into it (probably sometime next week)...

[charris]

@hayd Still pursuing this?

[ewmoore]

#368 seems related / duplicate.

[danielballan]

Can anyone point me and/or @hayd to where in the code this can be fixed. I spent some time looking, but I don't understand the numpy internals well enough yet....

[juliantaylor]

PyUFunc_O_O_method in ./numpy/core/src/umath/loops.c.src looks like the right spot

[eric-wieser]

Closed in #12700