There is a deprecation warning in place, try this:

>>> import warnings
>>> warnings.simplefilter('always')
>>> np.concatenate(([1,2],[3,4]), axis = 10)
__main__:1: DeprecationWarning: axis != 0 for ndim == 1; this will raise an error in future versions of numpy
array([1, 2, 3, 4])

It was introduced in 21a1d73 and 4475ead, almost 3 years ago. Perhaps 1.10 could be the deprecated future?

I guess we should look up when the first NumPy release containing those
commits was instead of just when they were written, but assuming that's
also 2+ years ago then raising an error in 1.10 seems reasonable to me.
On Apr 9, 2015 10:39 AM, "Jaime" notifications@github.com wrote:

There is a deprecation warning in place, try this:

import warnings
warnings.simplefilter('always')
np.concatenate(([1,2],[3,4]), axis = 10)
main:1: DeprecationWarning: axis != 0 for ndim == 1; this will raise an error in future versions of numpy
array([1, 2, 3, 4])

It was introduced in 21a1d73
21a1d73
and 4475ead
4475ead,
almost 3 years ago. Perhaps 1.10 could be the deprecated future?

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#5759 (comment).

This comment seems to indicate it went into effect in 1.7.

Fixed by #8584. Closing.