- Known deficiencies
- Quantities lose their units with some operations
- Quantities float comparison with np.isclose fails
- Table sorting can silently fail on MacOS X or Windows with Python 3 and Numpy < 1.6.2
- Remote data utilities in
astropy.utils.datafail on some Python distributions
- mmap support for
astropy.io.fitson GNU Hurd
- Bug with unicode endianness in
io.fitsfor big-endian processors
- Error ‘buffer’ does not have the buffer interface in
- Floating point precision issues on Python 2.6 on Microsoft Windows
- Color printing on Windows
- Build/installation/test issues
- Anaconda users should upgrade with
- Locale errors in MacOS X and Linux
- Creating a Time object fails with ValueError after upgrading Astropy
- Failing logging tests when running the tests in IPython
- Some docstrings can not be displayed in IPython < 0.13.2
- Installation fails on Mageia-2 or Mageia-3 distributions
- Crash on upgrading from Astropy 0.2 to a newer version
- Anaconda users should upgrade with
While most bugs and issues are managed using the astropy issue tracker, this document lists issues that are too difficult to fix, may require some intervention from the user to workaround, or are due to bugs in other projects or packages.
Issues listed on this page are grouped into two categories: The first is known issues and shortcomings in actual algorithms and interfaces that currently do not have fixes or workarounds, and that users should be aware of when writing code that uses Astropy. Some of those issues are still platform-specific, while others are very general. The second category is common issues that come up when configuring, building, or installing Astropy. This also includes cases where the test suite can report false negatives depending on the context/ platform on which it was run.
Quantities are subclassed from numpy’s
ndarray and in some numpy operations
(and in scipy operations using numpy internally) the subclass is ignored, which
means that either a plain array is returned, or a
Quantity without units.
>>> import astropy.units as u >>> import numpy as np >>> q = u.Quantity(np.arange(10.), u.m) >>> np.dot(q,q) 285.0 >>> np.hstack((q,q)) <Quantity [ 0., 1., 2., 3., 4., 5., 6., 7., 8., 9., 0., 1., 2., 3., 4., 5., 6., 7., 8., 9.] (Unit not initialised)>
Also in-place operations where the output is a normal
will drop the unit silently (at least in numpy <= 1.9):
>>> a = np.arange(10.) >>> a *= 1.*u.kg >>> a array([ 0., 1., 2., 3., 4., 5., 6., 7., 8., 9.])
Work-arounds are available for some cases. For the above:
>>> q.dot(q) <Quantity 285.0 m2> >>> u.Quantity([q, q]).flatten() <Quantity [ 0., 1., 2., 3., 4., 5., 6., 7., 8., 9., 0., 1., 2., 3., 4., 5., 6., 7., 8., 9.] m>
An incomplete list of specific functions which are known to exhibit this behavior follows.
- pandas DataFrame(s)
Comparing Quantities floats using the numpy function
isclose fails on
numpy 1.9 as the comparison between
b is made using the formula
This will result in the following traceback when using this with Quantities:
>>> from astropy import units as u, constants as const >>> import numpy as np >>> np.isclose(500* u.km/u.s, 300 * u.km / u.s) UnitsError: Can only apply 'add' function to dimensionless quantities when other argument is not a quantity (unless the latter is all zero/infinity/nan)
An easy solution is:
>>> np.isclose(500* u.km/u.s, 300 * u.km / u.s, atol=1e-8 * u.mm / u.s) array([False], dtype=bool)
In Python 3, prior to Numpy 1.6.2, there was a bug (in Numpy) that caused
sorting of structured arrays to silently fail under certain circumstances (for
example if the Table contains string columns) on MacOS X, Windows, and possibly
other platforms other than Linux. Since
Table.sort relies on Numpy to
internally sort the data, it is also affected by this bug. If you are using
Python 3, and need the sorting functionality for tables, we recommend updating
to a more recent version of Numpy.
Remote data utilities in
astropy.utils.data fail on some Python distributions¶
The remote data utilities in
astropy.utils.data depend on the Python
shelve module, which in some cases depends on the
bsddb module. Some Python distributions, including but
not limited to
- OS X, Python 2.7.5 via homebrew
- Linux, Python 2.7.6 via conda 
- Linux, Python 2.6.9 via conda
are built without support for the
bsddb module, resulting in an error
ImportError: No module named _bsddb
One workaround is to install the
On Hurd and possibly other platforms
flush() on memory-mapped files is not
implemented, so writing changes to a mmap’d FITS file may not be reliable and is
thus disabled. Attempting to open a FITS file in writeable mode with mmap will
result in a warning (and mmap will be disabled on the file automatically).
On big-endian processors (e.g. SPARC, PowerPC, MIPS), string columnn in FITS
files may not be correctly read when using the
Table.read interface. This
will be fixed in a subsequent bug fix release of Astropy (see bug report here)
For Python 2.7.x versions prior to 2.7.4, the
astropy.io.fits may under
certain circumstances output the following error:
TypeError: 'buffer' does not have the buffer interface
This can be resolved by upgrading to Python 2.7.4 or later (at the time of writing, the latest Python 2.7.x version is 2.7.9).
When converting floating point numbers to strings on Python 2.6 on a Microsoft Windows platform, some of the requested precision may be lost.
The easiest workaround is to install Python 2.7.
The Python issue: http://bugs.python.org/issue7117
Upgrading Astropy in the anaconda python distribution using
pip can result
in a corrupted install with a mix of files from the old version and the new
version. Anaconda users should update with
conda update astropy. There
may be a brief delay between the release of Astropy on PyPI and its release
conda package manager; users can check the availability of new
conda search astropy.
On MacOS X, you may see the following error when running
... ValueError: unknown locale: UTF-8
This is due to the
LC_CTYPE environment variable being incorrectly set to
UTF-8 by default, which is not a valid locale setting.
On MacOS X or Linux (or other platforms) you may also encounter the following error:
... stderr = stderr.decode(stdio_encoding) TypeError: decode() argument 1 must be str, not None
This also indicates that your locale is not set correctly.
To fix either of these issues, set this environment variable, as well as the
LC_ALL environment variables to e.g.
en_US.UTF-8 using, in
the case of
export LANG="en_US.UTF-8" export LC_ALL="en_US.UTF-8" export LC_CTYPE="en_US.UTF-8"
To avoid any issues in future, you should add this line to your e.g.
To test these changes, open a new terminal and type
locale, and you should
see something like:
$ locale LANG="en_US.UTF-8" LC_COLLATE="en_US.UTF-8" LC_CTYPE="en_US.UTF-8" LC_MESSAGES="en_US.UTF-8" LC_MONETARY="en_US.UTF-8" LC_NUMERIC="en_US.UTF-8" LC_TIME="en_US.UTF-8" LC_ALL="en_US.UTF-8"
If so, you can go ahead and try running
setup.py again (in the new
In some cases, have users have upgraded Astropy from an older version to v1.0
or greater they have run into the following crash when trying to create a
>>> datetime = Time('2012-03-01T13:08:00', scale='utc') Traceback (most recent call last): ... ValueError: Input values did not match any of the formats where the format keyword is optional [u'astropy_time', u'datetime', u'jyear_str', u'iso', u'isot', u'yday', u'byear_str']
This problem can occur when there is a version mismatch between the compiled ERFA library (this is included as part of Astropy in most distributions), and the version of the Astropy Python source.
This can have a number of causes. The most likely is that when installing the
new Astropy version, your previous Astropy version was not fully uninstalled
first, resulting in a mishmash of versions. Your best bet is to fully remove
Astropy from its installation path, and reinstall from scratch using your
preferred installation method. How to remove the old version may be a simple
matter if removing the entire
astropy/ directory from within the
site-packages directory it is installed in. However, if in doubt, ask
how best to uninstall packages from your preferred Python distribution.
Another possible cause of this, in particular for people developing on Astropy
and installing from a source checkout, is simply that your Astropy build
directory is unclean. To fix this, run
git clean -dfx. This removes
all build artifacts from the repository that aren’t normally tracked by git.
Make sure before running this that there are no untracked files in the
repository you intend to save. Then rebuild/reinstall from the clean repo.
When running the Astropy tests using
astropy.test() in an IPython
interpreter some of the tests in the
fail, depending on the version of IPython or other factors.
This is due to mutually incompatible behaviors in IPython and py.test, and is
not due to a problem with the test itself or the feature being tested.
Displaying long docstrings that contain Unicode characters may fail on some platforms in the IPython console (prior to IPython version 0.13.2):
>>> import astropy.units as u >>> u.Angstrom? ERROR: UnicodeEncodeError: 'ascii' codec can't encode character u'\xe5' in position 184: ordinal not in range(128) [IPython.core.page]
This can be worked around by changing the default encoding to
by adding the following to your
import sys sys.setdefaultencoding('utf-8')
Note that in general, this is not recommended, because it can hide other Unicode encoding bugs in your application. However, in general if your application does not deal with text processing and you just want docstrings to work, this may be acceptable.
The IPython issue: https://github.com/ipython/ipython/pull/2738
Building may fail with warning messages such as:
unable to find 'pow' or 'sincos'
at the linking phase. Upgrading the OS packages for Python should fix the issue, though an immediate workaround is to edit the file:
and search for the line that adds the option
-Wl,--no-undefined to the
LDFLAGS variable and remove that option.
It is possible for installation of a new version of Astropy, or upgrading of an
existing installation to crash due to not having permissions on the
~/.astropy/ directory (in your home directory) or some file or subdirectory
in that directory. In particular this can occur if you installed Astropy as
the root user (such as with
sudo) at any point. This can manifest in
several ways, but the most common is a traceback ending with
cannot import name config. To resolve this issue either run
sudo chown -R
<your_username> ~/.astropy or, if you don’t need anything in it you can blow
it away with
sudo rm -rf ~/.astropy.
See for example: https://github.com/astropy/astropy/issues/987
|||Continuum says this will be fixed in their next Python build.|