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astropy v1.0 Release Notes

Release Date: 2015-02-18 // about 9 years ago

  • General

    • Astropy now requires Numpy 1.6.0 or later.

    🆕 New Features

    astropy.analytic_functions

    • The astropy.analytic_functions was added to contain analytic functions useful for astronomy [#3077].

    astropy.coordinates

    • astropy.coordinates now has a full stack of frames allowing transformations from ICRS or other celestial systems down to Alt/Az coordinates. [#3217]

    • astropy.coordinates now has a get_sun function that gives the coordinates of the Sun at a specified time. [#3217]

    • SkyCoord now has to_pixel and from_pixel methods that convert between celestial coordinates as SkyCoord objects and pixel coordinates given an astropy.wcs.WCS object. [#3002]

    • SkyCoord now has search_around_sky and search_around_3d convenience methods that allow searching for all coordinates within a certain distance of another SkyCoord. [#2953]

    • SkyCoord can now accept a frame instance for the frame= keyword argument. [#3063]

    • SkyCoord now has a guess_from_table method that can be used to quickly create SkyCoord objects from an astropy.table.Table object. [#2951]

    • astropy.coordinates now has a Galactocentric frame, a coordinate frame centered on a (user specified) center of the Milky Way. [#2761, #3286]

    • SkyCoord now accepts more formats of the coordinate string when the representation has ra and dec attributes. [#2920]

    • SkyCoord can now accept lists of SkyCoord objects, frame objects, or representation objects and will combine them into a single object. [#3285]

    • Frames and SkyCoord instances now have a method is_equivalent_frame that can be used to check that two frames are equivalent (ignoring the data). [#3330]

    • The __repr__ of coordinate objects now shows scalar coordinates in the same format as vector coordinates. [#3350, 3448]

    astropy.cosmology

    • Added lookback_distance, which is c * lookback_time. [#3145]

    • ➕ Add baryonic matter density and dark matter only density parameters to cosmology objects [#2757].

    • ➕ Add a clone method to cosmology objects to allow copies of cosmological objects to be created with the specified variables modified [#2592].

    • Increase default numerical precision of z_at_value following the accurate by default, fast by explicit request model [#3074].

    • Cosmology functions that take a single (redshift) input now broadcast like numpy ufuncs. So, passing an arbitrarily shaped array of inputs will produce an output of the same shape. [#3178, #3194]

    astropy.io.ascii ^

    • Simplify the way new Reader classes are defined, allowing custom behavior entirely by overriding inherited class attributes instead of setting instance attributes in the Reader __init__ method. [#2812]

    • There is now a faster C/Cython engine available for reading and writing simple ASCII formats like CSV. Both are enabled by default, and fast reading will fall back on an ordinary reader in case of a parsing failure. Their behavior can be altered with the parameter fast_reader in read and fast_writer in write. [#2716]

    • 👉 Make Latex/AASTex tables use unit attribute of Column for output. [#3064]

    • 📇 Store comment lines encountered during reading in metadata of the output table via meta['comment_lines']. [#3222]

    • 📇 Write comment lines in Table metadata during output for all basic formats, IPAC, and fast writers. This functionality can be disabled with comment=False. [#3255]

    • ➕ Add reader / writer for the Enhanced CSV format which stores table and column meta data, in particular data type and unit. [#2319]

    astropy.io.fits ^

    • 0️⃣ The fitsdiff script ignores some things by default when comparing fits files (e.g. empty header lines). This adds a --exact option where nothing is ignored. [#2782, #3110]

    • The fitsheader script now takes a --keyword option to extract a specific keyword from the header of a FITS file, and a --table option to export headers into any of the data formats supported by astropy.table. [#2555, #2588]

    • 👍 Section now supports all advanced indexing features ndarray does (slices with any steps, integer arrays, boolean arrays, None, Ellipsis). It also properly returns scalars when this is appropriate. [#3148]

    astropy.io.votable

    • 📜 astropy.io.votable.parse now takes a datatype_mapping keyword argument to map invalid datatype names to valid ones in order to support non-compliant files. [#2675]

    astropy.modeling ^

    • ➕ Added the capability of creating new "compound" models by combining existing models using arithmetic operators. See the "What's New in 1.0" page in the Astropy documentation for more details. [#3231]

    • A new custom_model decorator/factory function has been added for converting normal functions to Model classes that can work within the Astropy modeling framework. This replaces the old custom_model_1d function which is now deprecated. The new function works the same as the old one but is less limited in the types of models it can be used to created. [#1763]

    • The Model and Fitter classes have .registry attributes which provide sets of all loaded Model and Fitter classes (this is useful for building UIs for models and fitting). [#2725]

    • A dict-like meta member was added to Model. it is to be used to store any optional information which is relevant to a project and is not in the standard Model class. [#2189]

    • ➕ Added Ellipse2D model. [#3124]

    astropy.nddata ^

    • 🆕 New array-related utility functions in astropy.nddata.utils for adding and removing arrays from other arrays with different sizes/shapes. [#3201]

    • 🆕 New metaclass NDDataBase for enforcing the nddata interface in subclasses without restricting implementation of the data storage. [#2905]

    • 🆕 New mixin classes NDSlicingMixin for slicing, NDArithmeticMixin for arithmetic operations, and NDIOMixin for input/ouput in NDData. [#2905]

    • ➕ Added a decorator support_nddata that can be used to write functions that can either take separate arguments or NDData objects. [#2855]

    astropy.stats ^

    • ➕ Added mad_std() function. [#3208]

    • Added gaussian_fwhm_to_sigma and gaussian_sigma_to_fwhm constants. [#3208]

    • New function sigma_clipped_stats which can be used to quickly get common statistics for an array, using sigma clipping at the same time. [#3201]

    astropy.table ^

    • 🔄 Changed the internal implementation of the Table class changed so that it no longer uses numpy structured arrays as the core table data container. [#2790, #3179]

    • Tables can now be written to an html file that includes interactive browsing capabilities. To write out to this format, use Table.write('filename.html', format='jsviewer'). [#2875]

    • A quantity property and to method were added to Table columns that allow the column values to be easily converted to astropy.units.Quantity objects. [#2950]

    • ➕ Add unique convenience method to table. [#3185]

    ✅ astropy.tests ^

    • Added a new Quantity-aware assert_quantity_allclose. [#3273]

    astropy.time ^

    • Time can now handle arbitrary array dimensions, with operations following standard numpy broadcasting rules. [#3138]

    astropy.units ^

    • 👌 Support for VOUnit has been updated to be compliant with version 1.0 of the standard. [#2901]

    • ➕ Added an insert method to insert values into a Quantity object. This is similar to the numpy.insert function. [#3049]

    • When viewed in IPython, Quantity objects with array values now render using LaTeX and scientific notation. [#2271]

    • ➕ Added units.quantity_input decorator to validate quantity inputs to a function for unit compatibility. [#3072]

    • ➕ Added units.astronomical_unit as a long form for units.au. [#3303]

    astropy.utils ^

    • ➕ Added a new decorator astropy.utils.wraps which acts as a replacement for the standard library's functools.wraps, the only difference being that the decorated function also preserves the wrapped function's call signature. [#2849]

    • astropy.utils.compat.numpy has been revised such that it can include patched versions of routines from newer numpy versions. The first addition is a version of broadcast_arrays that can be used with Quantity and other ndarray subclasses (using the subok=True flag). [#2327]

    • ➕ Added astropy.utils.resolve_name which returns a member of a module or class given the fully qualified dotted name of that object as a string. [#3389]

    • ➕ Added astropy.utils.minversion which can be used to check minimum version requirements of Python modules (to test for specific features and/ or bugs and the like). [#3389]

    astropy.visualization

    • Created astropy.visualization module and added functionality relating to image normalization (i.e. stretching and scaling) as well as a new script fits2bitmap that can produce a bitmap image from a FITS file. [#3201]

    • 💅 Added dictionary astropy.visualization.mpl_style.astropy_mpl_style which can be used to set a uniform plotstyle specifically for tutorials that is improved compared to matplotlib defaults. [#2719, #2787, #3200]

    astropy.wcs ^

    • ⬆️ wcslib has been upgraded to version 4.25. This brings a single new feature:

    • 0️⃣ equinox and radesys will now be given default values conforming with the WCS specification if EQUINOXa and RADESYSa, respectively, are not present in the header.

    • The minimum required version of wcslib is now 4.24. [#2503]

    • Added a new function wcs_to_celestial_frame that can be used to find the astropy.coordinates celestial frame corresponding to a particular WCS. [#2730]

    • 👍 astropy.wcs.WCS.compare now supports a tolerance keyword argument to allow for approximate comparison of floating-point values. [#2503]

    • added pixel_scale_matrix, celestial, is_celestial, and has_celestial convenience attributes. Added proj_plane_pixel_scales, proj_plane_pixel_area, and non_celestial_pixel_scales utility functions for retrieving WCS pixel scale and area information [#2832, #3304]

    • Added two functions pixel_to_skycoord and skycoord_to_pixel that make it easy to convert between SkyCoord objects and pixel coordinates. [#2885]

    • all_world2pix now uses a much more sophisticated and complete algorithm to iteratively compute the inverse WCS transform. [#2816]

    • ➕ Add ability to use WCS object to define projections in Matplotlib, using the WCSAxes package. [#3183]

    • Added is_proj_plane_distorted for testing if pixels are distorted. [#3329]

    Misc ^

    • 📦 astropy._erfa was added as a new subpackage wrapping the functionality of the ERFA library in python. This is primarily of use for other astropy subpackages, but the API may be made more public in the future. [#2992]

    API Changes

    astropy.coordinates

    • Subclasses of BaseCoordinateFrame which define a custom repr should be aware of the format expected in SkyCoord.__repr__(), which changed in this release. [#2704, #2882]

    • 🚚 The CartesianPoints class (deprecated in v0.4) has now been removed. [#2990]

    • The previous astropy.coordinates.builtin_frames module is now a subpackage. Everything that was in the astropy.coordinates.builtin_frames module is still accessible from the new package, but the classes are now in separate modules. This should have no direct impact at the user level. [#3120]

    • 👌 Support for passing a frame as a positional argument in the SkyCoord class has now been deprecated, except in the case where a frame with data is passed as the sole positional argument. [#3152]

    • Improved __repr__ of coordinate objects representing a single coordinate point for the sake of easier copy/pasting. [#3350]

    astropy.cosmology

    • The functional interface to the cosmological routines as well as set_current and get_current (deprecated in v0.4) have now been removed. [#2990]

    astropy.io.ascii ^

    • ➕ Added a new argument to htmldict in the HTML reader named parser, which allows the user to specify which parser BeautifulSoup should use as a backend. [#2815]

    • ➕ Add FixedWidthTwoLine reader to guessing. This will allows to read tables that a copied from screen output like print my_table to be read automatically. Discussed in #3025 and #3099 [#3109]

    astropy.io.fits ^

    • A new optional argument cache has been added to astropy.io.fits.open(). When opening a FITS file from a URL, cache is a boolean value specifying whether or not to save the file locally in Astropy's download cache (True by default). [#3041]

    astropy.modeling ^

    • Model classes should now specify inputs and outputs class attributes instead of the old n_inputs and n_outputs. These should be tuples providing human-readable labels for all inputs and outputs of the model. The length of the tuple indicates the numbers of inputs and outputs. See "What's New in Astropy 1.0" for more details. [#2835]

    • It is no longer necessary to include __init__ or __call__ definitions in Model subclasses if all they do is wrap the super-method in order to provide a nice call signature to the docs. The inputs class attribute is now used to generate a nice call signature, so these methods should only be overridden by Model subclasses in order to provide new functionality. [#2835]

    • 0️⃣ Most models included in Astropy now have sensible default values for most or all of their parameters. Call help(ModelClass) on any model to check what those defaults are. Most of them time they should be overridden, but some of them are useful (for example spatial offsets are always set at the origin by default). Another rule of thumb is that, where possible, default parameters are set so that the model is a no-op, or close to it, by default. [#2932]

    • The Model.inverse method has been changed to a property, so that now accessing model.inverse on a model returns a new model that implements that model's inverse, and calling model.inverse(...)on some independent variable computes the value of the inverse (similar to what the oldModel.invert()` method was meant to do). [#3024]

    • 🚚 The Model.invert() method has been removed entirely (it was never implemented and there should not be any existing code that relies on it). [#3024]

    • custom_model_1d is deprecated in favor of the new custom_model (see "New Features" above). [#1763]

    • 🚚 The Model.param_dim property (deprecated in v0.4) has now been removed. [#2990]

    • The Beta1D and Beta2D models have been renamed to Moffat1D and Moffat2D. [#3029]

    astropy.nddata ^

    • 🚚 flags, shape, size, dtype and ndim properties removed from astropy.nddata.NDData. [#2905]

    • Arithmetic operations, uncertainty propagation, slicing and automatic conversion to a numpy array removed from astropy.nddata.NDData. The class astropy.nddata.NDDataArray is functionally equivalent to the old NDData. [#2905]

    astropy.table ^

    • 🚚 The Column.units property (deprecated in v0.3) has now been removed. [#2990]

    • 🗄 The Row.data and Table._data attributes have been deprecated related to the change in Table implementation. They are replaced by Row.as_void() and Table.as_array() methods, respectively. [#2790]

    • 🚚 The Table.create_mask method has been removed. This undocumented method was a development orphan and would cause corruption of the table if called. [#2790]

    • The return type for integer item access to a Column (e.g. col[12] or t['a'][12]) is now always a numpy scalar, numpy ndarray, or numpy MaskedArray. Previously if the column was multidimensional then a Column object would be returned. [#3095]

    • The representation of Table and Column objects has been changed to be formatted similar to the print output. [#3239]

    astropy.time ^

    • 🗄 The Time.val and Time.vals properties (deprecated in v0.3) and the Time.lon, and Time.lat properties (deprecated in v0.4) have now been removed. [#2990]

    • ➕ Add decimalyear format that represents time as a decimal year. [#3265]

    astropy.units ^

    • 👌 Support for VOUnit has been updated to be compliant with version 1.0 of the standard. This means that some VOUnit strings that were rejected before are now acceptable. [#2901] Notably:

    • 🛠 SI prefixes are supported on most units

    • 🛠 Binary prefixes are supported on "bits" and "bytes"

    • Custom units can be defined "inline" by placing them between single quotes.

    • 🗄 Unit.get_converter has been deprecated. It is not strictly necessary for end users, and it was confusing due to lack of support for Quantity objects. [#3456]

    astropy.utils ^

    • 🚚 Some members of astropy.utils.misc were moved into new submodules. Specifically:

    • 🗄 deprecated, deprecated_attribute, and lazyproperty -> astropy.utils.decorators

    • find_current_module, find_mod_objs -> astropy.utils.introspection

    All of these functions can be imported directly from astropy.utils which should be preferred over referencing individual submodules of astropy.utils. [#2857]

    • 🗄 The ProgressBar.iterate class method (deprecated in v0.3) has now been removed. [#2990]

    • ⚡️ Updated astropy/utils/console.py ProgressBar() module to display output to IPython notebook with the addition of an interactive kwarg. [#2658, #2789]

    astropy.wcs ^

    • 🚚 The WCS.calcFootprint method (deprecated in v0.4) has now been removed. [#2990]

    • ⚠ An invalid unit in a CUNITn keyword now displays a warning and returns a UnrecognizedUnit instance rather than raising an exception [#3190]

    🐛 Bug Fixes

    astropy.convolution

    • astropy.convolution.discretize_model now handles arbitrary callables correctly [#2274].

    astropy.coordinates

    • Angle.to_string now outputs unicode arrays instead of object arrays. [#2981]

    • SkyCoord.to_string no longer gives an error when used with an array coordinate with more than one dimension. [#3340]

    • 🛠 Fixed support for subclasses of UnitSphericalRepresentation and SphericalRepresentation [#3354, #3366]

    • 🛠 Fixed latex display of array angles in IPython notebook. [#3480]

    astropy.io.ascii ^

    • 0️⃣ In the CommentedHeader the data_start parameter now defaults to 0, which is the first uncommented line. Discussed in #2692. [#3054]

    • 🛠 Position lines in FixedWidthTwoLine reader could consist of many characters. Now, only one character in addition to the delimiter is allowed. This bug was discovered as part of [#3109]

    • The IPAC table writer now consistently uses the fill_values keyword to specify the output null values. Previously the behavior was inconsistent or incorrect. [#3259]

    • The IPAC table reader now correctly interprets abbreviated column types. [#3279]

    • Tables that look almost, but not quite like DAOPhot tables could cause guessing to fail. [#3342]

    astropy.io.fits ^

    • 🛠 Fixed the problem in fits.open of some filenames with colon (:) in the name being recognized as URLs instead of file names. [#3122]

    • Setting memmap=True in fits.open and related functions now raises a ValueError if opening a file in memory-mapped mode is impossible. [#2298]

    • CONTINUE cards no longer end the value of the final card in the series with an ampersand, per the specification of the CONTINUE card convention. [#3282]

    • 🛠 Fixed a crash that occurred when reading an ASCII table containing zero-precision floating point fields. [#3422]

    • When a float field for an ASCII table has zero-precision a decimal point (with no digits following it) is still written to the field as long as there is space for it, as recommended by the FITS standard. This makes it less ambiguous that these columns should be interpreted as floats. [#3422]

    astropy.logger ^

    • 🛠 Fix a bug that occurred when displaying warnings that produced an error message dictionary changed size during iteration. [#3353]

    astropy.modeling ^

    • 🛠 Fixed a bug in SLSQPLSQFitter where the maxiter argument was not passed correctly to the optimizer. [#3339]

    astropy.table ^

    • 🛠 Fix a problem where table.hstack fails to stack multiple references to the same table, e.g. table.hstack([t, t]). [#2995]

    • 🛠 Fixed a problem where table.vstack and table.hstack failed to stack a single table, e.g. table.vstack([t]). [#3313]

    • 🛠 Fix a problem when doing nested iterators on a single table. [#3358]

    • 🛠 Fix an error when an empty list, tuple, or ndarray is used for item access within a table. This now returns the table with no rows. [#3442]

    astropy.time ^

    • When creating a Time object from a datetime object the time zone info is now correctly used. [#3160]

    • For Time objects, it is now checked that numerical input is finite. [#3396]

    astropy.units ^

    • ➕ Added a latex_inline unit format that returns the units in LaTeX math notation with negative exponents instead of fractions [#2622].

    • 🗄 When using a unit that is deprecated in a given unit format, non-deprecated alternatives will be suggested. [#2806] For example::

      import astropy.units as u u.Unit('Angstrom', format='fits') WARNING: UnitsWarning: The unit 'Angstrom' has been deprecated in the FITS standard. Suggested: nm (with data multiplied by 0.1). [astropy.units.format.utils]

    astropy.utils ^

    • 🗄 treat_deprecations_as_exceptions has been fixed to recognize Astropy deprecation warnings. [#3015]

    • Converted representation of progress bar units without suffix from float to int in console.human_file_size. [#2201, #2202, #2721, #3299]

    astropy.wcs ^

    • astropy.wcs.WCS.sub now accepts unicode strings as input on Python 2.x [#3356]

    Misc ^

    • ✅ Some modules and tests that would crash upon import when using a non-final release of Numpy (e.g. 1.9.0rc1). [#3471]

    Other Changes and Additions

    • ⚡️ The bundled copy of astropy-helpers has been updated to v1.0. [#3515]

    • ⚡️ Updated astropy.extern.configobj to Version 5. Version 5 uses six and the same code covers both Python 2 and Python 3. [#3149]

    astropy.coordinates

    • The repr of SkyCoord and coordinate frame classes now separate frame attributes and coordinate information. [#2704, #2882]

    astropy.io.fits ^

    • Overwriting an existing file using the clobber=True option no longer displays a warning message. [#1963]

    • fits.open no longer catches OSError exceptions on missing or unreadable files-- instead it raises the standard Python exceptions in such cases. [#2756, #2785]

    astropy.table ^

    • Sped up setting of Column slices by an order of magnitude. [#2994, #3020]

    • ⚡️ Updated the bundled six module to version 1.7.3 and made 1.7.3 the minimum acceptable version of six. [#2814]

    • The version of ERFA included with Astropy is now v1.1.1 [#2971]

    • The code base is now fully Python 2 and 3 compatible and no longer requires 2to3. [#2033]

    • funcsigs <https://pypi.python.org/pypi/funcsigs>_ is included in utils.compat, but defaults to the inspect module components where available (3.3+) [#3151].

    • ✅ The list of modules displayed in the pytest header can now be customized. [#3157]

    • 🏗 jinja2 <http://jinja.pocoo.org/docs/dev/>_>=2.7 is now required to build the source code from the git repository, in order to allow the ERFA wrappers to be generated. [#3166]