`numpy.exceptions:AxisError`

source: /numpy/exceptions.py:108

Signature

class AxisError(axis, ndim = None, msg_prefix = None)

Members

Summary

Axis supplied was invalid.

Extended Summary

This is raised whenever an axis parameter is specified that is larger than the number of array dimensions. For compatibility with code written against older numpy versions, which raised a mixture of ValueError and IndexError for this situation, this exception subclasses both to ensure that except ValueError and except IndexError statements continue to catch AxisError.

Parameters

axis : int or str: The out of bounds axis or a custom exception message. If an axis is provided, then ndim should be specified as well.
ndim : int, optional: The number of array dimensions.
msg_prefix : str, optional: A prefix for the exception message.

Attributes

axis : int, optional: The out of bounds axis or None if a custom exception message was provided. This should be the axis as passed by the user, before any normalization to resolve negative indices.
versionadded 1.22
ndim : int, optional: The number of array dimensions or None if a custom exception message was provided.
versionadded 1.22

Examples

import numpy as np
array_1d = np.arange(10)
np.cumsum(array_1d, axis=1)

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Traceback (most recent call last):
  File "<doctest numpy.exceptions:AxisError[0]>", line 1, in <module>
    np.cumsum(array_1d, axis=1)
    ~~~~~~~~~^^^^^^^^^^^^^^^^^^
  File "/opt/hostedtoolcache/Python/3.14.7/x64/lib/python3.14/site-packages/numpy/_core/fromnumeric.py", line 2914, in cumsum
    return _wrapfunc(a, 'cumsum', axis=axis, dtype=dtype, out=out)
  File "/opt/hostedtoolcache/Python/3.14.7/x64/lib/python3.14/site-packages/numpy/_core/fromnumeric.py", line 54, in _wrapfunc
    return bound(*args, **kwds)
numpy.exceptions.AxisError: axis 1 is out of bounds for array of dimension 1

Negative axes are preserved:

np.cumsum(array_1d, axis=-2)

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Traceback (most recent call last):
  File "<doctest numpy.exceptions:AxisError[0]>", line 1, in <module>
    np.cumsum(array_1d, axis=-2)
    ~~~~~~~~~^^^^^^^^^^^^^^^^^^^
  File "/opt/hostedtoolcache/Python/3.14.7/x64/lib/python3.14/site-packages/numpy/_core/fromnumeric.py", line 2914, in cumsum
    return _wrapfunc(a, 'cumsum', axis=axis, dtype=dtype, out=out)
  File "/opt/hostedtoolcache/Python/3.14.7/x64/lib/python3.14/site-packages/numpy/_core/fromnumeric.py", line 54, in _wrapfunc
    return bound(*args, **kwds)
numpy.exceptions.AxisError: axis -2 is out of bounds for array of dimension 1

The class constructor generally takes the axis and arrays' dimensionality as arguments:

print(np.exceptions.AxisError(2, 1, msg_prefix='error'))

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error: axis 2 is out of bounds for array of dimension 1

Alternatively, a custom exception message can be passed:

print(np.exceptions.AxisError('Custom error message'))

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Custom error message

Aliases

numpy.exceptions.AxisError