Source code for astropy.utils.misc

# -*- coding: utf-8 -*-
# Licensed under a 3-clause BSD style license - see LICENSE.rst
"""
A "grab bag" of relatively small general-purpose utilities that don't have
a clear module/package to live in.
"""

import abc
import contextlib
import difflib
import inspect
import json
import os
import signal
import sys
import traceback
import unicodedata
import locale
import threading
import re

from itertools import zip_longest
from contextlib import contextmanager
from collections import defaultdict, OrderedDict

from astropy.utils.decorators import deprecated


__all__ = ['isiterable', 'silence', 'format_exception', 'NumpyRNGContext',
           'find_api_page', 'is_path_hidden', 'walk_skip_hidden',
           'JsonCustomEncoder', 'indent',
           'OrderedDescriptor', 'OrderedDescriptorContainer',
           'ShapedLikeNDArray', 'check_broadcast', 'IncompatibleShapeError',
           'dtype_bytes_or_chars', 'unbroadcast']


[docs]def isiterable(obj): """Returns `True` if the given object is iterable.""" try: iter(obj) return True except TypeError: return False
[docs]def indent(s, shift=1, width=4): """Indent a block of text. The indentation is applied to each line.""" indented = '\n'.join(' ' * (width * shift) + l if l else '' for l in s.splitlines()) if s[-1] == '\n': indented += '\n' return indented
class _DummyFile: """A noop writeable object.""" def write(self, s): pass
[docs]@contextlib.contextmanager def silence(): """A context manager that silences sys.stdout and sys.stderr.""" old_stdout = sys.stdout old_stderr = sys.stderr sys.stdout = _DummyFile() sys.stderr = _DummyFile() yield sys.stdout = old_stdout sys.stderr = old_stderr
[docs]def format_exception(msg, *args, **kwargs): """ Given an exception message string, uses new-style formatting arguments ``{filename}``, ``{lineno}``, ``{func}`` and/or ``{text}`` to fill in information about the exception that occurred. For example: try: 1/0 except: raise ZeroDivisionError( format_except('A divide by zero occurred in {filename} at ' 'line {lineno} of function {func}.')) Any additional positional or keyword arguments passed to this function are also used to format the message. .. note:: This uses `sys.exc_info` to gather up the information needed to fill in the formatting arguments. Since `sys.exc_info` is not carried outside a handled exception, it's not wise to use this outside of an ``except`` clause - if it is, this will substitute '<unkonwn>' for the 4 formatting arguments. """ tb = traceback.extract_tb(sys.exc_info()[2], limit=1) if len(tb) > 0: filename, lineno, func, text = tb[0] else: filename = lineno = func = text = '<unknown>' return msg.format(*args, filename=filename, lineno=lineno, func=func, text=text, **kwargs)
[docs]class NumpyRNGContext: """ A context manager (for use with the ``with`` statement) that will seed the numpy random number generator (RNG) to a specific value, and then restore the RNG state back to whatever it was before. This is primarily intended for use in the astropy testing suit, but it may be useful in ensuring reproducibility of Monte Carlo simulations in a science context. Parameters ---------- seed : int The value to use to seed the numpy RNG Examples -------- A typical use case might be:: with NumpyRNGContext(<some seed value you pick>): from numpy import random randarr = random.randn(100) ... run your test using `randarr` ... #Any code using numpy.random at this indent level will act just as it #would have if it had been before the with statement - e.g. whatever #the default seed is. """ def __init__(self, seed): self.seed = seed def __enter__(self): from numpy import random self.startstate = random.get_state() random.seed(self.seed) def __exit__(self, exc_type, exc_value, traceback): from numpy import random random.set_state(self.startstate)
[docs]def find_api_page(obj, version=None, openinbrowser=True, timeout=None): """ Determines the URL of the API page for the specified object, and optionally open that page in a web browser. .. note:: You must be connected to the internet for this to function even if ``openinbrowser`` is `False`, unless you provide a local version of the documentation to ``version`` (e.g., ``file:///path/to/docs``). Parameters ---------- obj The object to open the docs for or its fully-qualified name (as a str). version : str The doc version - either a version number like '0.1', 'dev' for the development/latest docs, or a URL to point to a specific location that should be the *base* of the documentation. Defaults to latest if you are on aren't on a release, otherwise, the version you are on. openinbrowser : bool If `True`, the `webbrowser` package will be used to open the doc page in a new web browser window. timeout : number, optional The number of seconds to wait before timing-out the query to the astropy documentation. If not given, the default python stdlib timeout will be used. Returns ------- url : str The loaded URL Raises ------ ValueError If the documentation can't be found """ import webbrowser import urllib.request from zlib import decompress if (not isinstance(obj, str) and hasattr(obj, '__module__') and hasattr(obj, '__name__')): obj = obj.__module__ + '.' + obj.__name__ elif inspect.ismodule(obj): obj = obj.__name__ if version is None: from astropy import version if version.release: version = 'v' + version.version else: version = 'dev' if '://' in version: if version.endswith('index.html'): baseurl = version[:-10] elif version.endswith('/'): baseurl = version else: baseurl = version + '/' elif version == 'dev' or version == 'latest': baseurl = 'http://devdocs.astropy.org/' else: baseurl = f'https://docs.astropy.org/en/{version}/' # Custom request headers; see # https://github.com/astropy/astropy/issues/8990 req = urllib.request.Request( baseurl + 'objects.inv', headers={'User-Agent': f'Astropy/{version}'}) if timeout is None: uf = urllib.request.urlopen(req) else: uf = urllib.request.urlopen(req, timeout=timeout) try: oiread = uf.read() # need to first read/remove the first four lines, which have info before # the compressed section with the actual object inventory idx = -1 headerlines = [] for _ in range(4): oldidx = idx idx = oiread.index(b'\n', oldidx + 1) headerlines.append(oiread[(oldidx+1):idx].decode('utf-8')) # intersphinx version line, project name, and project version ivers, proj, vers, compr = headerlines if 'The remainder of this file is compressed using zlib' not in compr: raise ValueError('The file downloaded from {} does not seem to be' 'the usual Sphinx objects.inv format. Maybe it ' 'has changed?'.format(baseurl + 'objects.inv')) compressed = oiread[(idx+1):] finally: uf.close() decompressed = decompress(compressed).decode('utf-8') resurl = None for l in decompressed.strip().splitlines(): ls = l.split() name = ls[0] loc = ls[3] if loc.endswith('$'): loc = loc[:-1] + name if name == obj: resurl = baseurl + loc break if resurl is None: raise ValueError(f'Could not find the docs for the object {obj}') elif openinbrowser: webbrowser.open(resurl) return resurl
def signal_number_to_name(signum): """ Given an OS signal number, returns a signal name. If the signal number is unknown, returns ``'UNKNOWN'``. """ # Since these numbers and names are platform specific, we use the # builtin signal module and build a reverse mapping. signal_to_name_map = dict((k, v) for v, k in signal.__dict__.items() if v.startswith('SIG')) return signal_to_name_map.get(signum, 'UNKNOWN') if sys.platform == 'win32': import ctypes def _has_hidden_attribute(filepath): """ Returns True if the given filepath has the hidden attribute on MS-Windows. Based on a post here: https://stackoverflow.com/questions/284115/cross-platform-hidden-file-detection """ if isinstance(filepath, bytes): filepath = filepath.decode(sys.getfilesystemencoding()) try: attrs = ctypes.windll.kernel32.GetFileAttributesW(filepath) result = bool(attrs & 2) and attrs != -1 except AttributeError: result = False return result else: def _has_hidden_attribute(filepath): return False
[docs]def is_path_hidden(filepath): """ Determines if a given file or directory is hidden. Parameters ---------- filepath : str The path to a file or directory Returns ------- hidden : bool Returns `True` if the file is hidden """ name = os.path.basename(os.path.abspath(filepath)) if isinstance(name, bytes): is_dotted = name.startswith(b'.') else: is_dotted = name.startswith('.') return is_dotted or _has_hidden_attribute(filepath)
[docs]def walk_skip_hidden(top, onerror=None, followlinks=False): """ A wrapper for `os.walk` that skips hidden files and directories. This function does not have the parameter ``topdown`` from `os.walk`: the directories must always be recursed top-down when using this function. See also -------- os.walk : For a description of the parameters """ for root, dirs, files in os.walk( top, topdown=True, onerror=onerror, followlinks=followlinks): # These lists must be updated in-place so os.walk will skip # hidden directories dirs[:] = [d for d in dirs if not is_path_hidden(d)] files[:] = [f for f in files if not is_path_hidden(f)] yield root, dirs, files
[docs]class JsonCustomEncoder(json.JSONEncoder): """Support for data types that JSON default encoder does not do. This includes: * Numpy array or number * Complex number * Set * Bytes * astropy.UnitBase * astropy.Quantity Examples -------- >>> import json >>> import numpy as np >>> from astropy.utils.misc import JsonCustomEncoder >>> json.dumps(np.arange(3), cls=JsonCustomEncoder) '[0, 1, 2]' """
[docs] def default(self, obj): from astropy import units as u import numpy as np if isinstance(obj, u.Quantity): return dict(value=obj.value, unit=obj.unit.to_string()) if isinstance(obj, (np.number, np.ndarray)): return obj.tolist() elif isinstance(obj, complex): return [obj.real, obj.imag] elif isinstance(obj, set): return list(obj) elif isinstance(obj, bytes): # pragma: py3 return obj.decode() elif isinstance(obj, (u.UnitBase, u.FunctionUnitBase)): if obj == u.dimensionless_unscaled: obj = 'dimensionless_unit' else: return obj.to_string() return json.JSONEncoder.default(self, obj)
def strip_accents(s): """ Remove accents from a Unicode string. This helps with matching "ångström" to "angstrom", for example. """ return ''.join( c for c in unicodedata.normalize('NFD', s) if unicodedata.category(c) != 'Mn') def did_you_mean(s, candidates, n=3, cutoff=0.8, fix=None): """ When a string isn't found in a set of candidates, we can be nice to provide a list of alternatives in the exception. This convenience function helps to format that part of the exception. Parameters ---------- s : str candidates : sequence of str or dict of str keys n : int The maximum number of results to include. See `difflib.get_close_matches`. cutoff : float In the range [0, 1]. Possibilities that don't score at least that similar to word are ignored. See `difflib.get_close_matches`. fix : callable A callable to modify the results after matching. It should take a single string and return a sequence of strings containing the fixed matches. Returns ------- message : str Returns the string "Did you mean X, Y, or Z?", or the empty string if no alternatives were found. """ if isinstance(s, str): s = strip_accents(s) s_lower = s.lower() # Create a mapping from the lower case name to all capitalization # variants of that name. candidates_lower = {} for candidate in candidates: candidate_lower = candidate.lower() candidates_lower.setdefault(candidate_lower, []) candidates_lower[candidate_lower].append(candidate) # The heuristic here is to first try "singularizing" the word. If # that doesn't match anything use difflib to find close matches in # original, lower and upper case. if s_lower.endswith('s') and s_lower[:-1] in candidates_lower: matches = [s_lower[:-1]] else: matches = difflib.get_close_matches( s_lower, candidates_lower, n=n, cutoff=cutoff) if len(matches): capitalized_matches = set() for match in matches: capitalized_matches.update(candidates_lower[match]) matches = capitalized_matches if fix is not None: mapped_matches = [] for match in matches: mapped_matches.extend(fix(match)) matches = mapped_matches matches = list(set(matches)) matches = sorted(matches) if len(matches) == 1: matches = matches[0] else: matches = (', '.join(matches[:-1]) + ' or ' + matches[-1]) return f'Did you mean {matches}?' return '' @deprecated('4.0', alternative='Sphinx>=1.7 automatically inherits docstring') class InheritDocstrings(type): """ This metaclass makes methods of a class automatically have their docstrings filled in from the methods they override in the base class. If the class uses multiple inheritance, the docstring will be chosen from the first class in the bases list, in the same way as methods are normally resolved in Python. If this results in selecting the wrong docstring, the docstring will need to be explicitly included on the method. For example:: >>> import warnings >>> with warnings.catch_warnings(): ... # Ignore deprecation warning ... warnings.simplefilter('ignore') ... from astropy.utils.misc import InheritDocstrings ... class A(metaclass=InheritDocstrings): ... def wiggle(self): ... "Wiggle the thingamajig" ... pass ... class B(A): ... def wiggle(self): ... pass >>> B.wiggle.__doc__ u'Wiggle the thingamajig' """ def __init__(cls, name, bases, dct): def is_public_member(key): return ( (key.startswith('__') and key.endswith('__') and len(key) > 4) or not key.startswith('_')) for key, val in dct.items(): if ((inspect.isfunction(val) or inspect.isdatadescriptor(val)) and is_public_member(key) and val.__doc__ is None): for base in cls.__mro__[1:]: super_method = getattr(base, key, None) if super_method is not None: val.__doc__ = super_method.__doc__ break super().__init__(name, bases, dct)
[docs]class OrderedDescriptor(metaclass=abc.ABCMeta): """ Base class for descriptors whose order in the class body should be preserved. Intended for use in concert with the `OrderedDescriptorContainer` metaclass. Subclasses of `OrderedDescriptor` must define a value for a class attribute called ``_class_attribute_``. This is the name of a class attribute on the *container* class for these descriptors, which will be set to an `~collections.OrderedDict` at class creation time. This `~collections.OrderedDict` will contain a mapping of all class attributes that were assigned instances of the `OrderedDescriptor` subclass, to the instances themselves. See the documentation for `OrderedDescriptorContainer` for a concrete example. Optionally, subclasses of `OrderedDescriptor` may define a value for a class attribute called ``_name_attribute_``. This should be the name of an attribute on instances of the subclass. When specified, during creation of a class containing these descriptors, the name attribute on each instance will be set to the name of the class attribute it was assigned to on the class. .. note:: Although this class is intended for use with *descriptors* (i.e. classes that define any of the ``__get__``, ``__set__``, or ``__delete__`` magic methods), this base class is not itself a descriptor, and technically this could be used for classes that are not descriptors too. However, use with descriptors is the original intended purpose. """ # This id increments for each OrderedDescriptor instance created, so they # are always ordered in the order they were created. Class bodies are # guaranteed to be executed from top to bottom. Not sure if this is # thread-safe though. _nextid = 1 @property @abc.abstractmethod def _class_attribute_(self): """ Subclasses should define this attribute to the name of an attribute on classes containing this subclass. That attribute will contain the mapping of all instances of that `OrderedDescriptor` subclass defined in the class body. If the same descriptor needs to be used with different classes, each with different names of this attribute, multiple subclasses will be needed. """ _name_attribute_ = None """ Subclasses may optionally define this attribute to specify the name of an attribute on instances of the class that should be filled with the instance's attribute name at class creation time. """ def __init__(self, *args, **kwargs): # The _nextid attribute is shared across all subclasses so that # different subclasses of OrderedDescriptors can be sorted correctly # between themselves self.__order = OrderedDescriptor._nextid OrderedDescriptor._nextid += 1 super().__init__() def __lt__(self, other): """ Defined for convenient sorting of `OrderedDescriptor` instances, which are defined to sort in their creation order. """ if (isinstance(self, OrderedDescriptor) and isinstance(other, OrderedDescriptor)): try: return self.__order < other.__order except AttributeError: raise RuntimeError( 'Could not determine ordering for {} and {}; at least ' 'one of them is not calling super().__init__ in its ' '__init__.'.format(self, other)) else: return NotImplemented
[docs]class OrderedDescriptorContainer(type): """ Classes should use this metaclass if they wish to use `OrderedDescriptor` attributes, which are class attributes that "remember" the order in which they were defined in the class body. Every subclass of `OrderedDescriptor` has an attribute called ``_class_attribute_``. For example, if we have .. code:: python class ExampleDecorator(OrderedDescriptor): _class_attribute_ = '_examples_' Then when a class with the `OrderedDescriptorContainer` metaclass is created, it will automatically be assigned a class attribute ``_examples_`` referencing an `~collections.OrderedDict` containing all instances of ``ExampleDecorator`` defined in the class body, mapped to by the names of the attributes they were assigned to. When subclassing a class with this metaclass, the descriptor dict (i.e. ``_examples_`` in the above example) will *not* contain descriptors inherited from the base class. That is, this only works by default with decorators explicitly defined in the class body. However, the subclass *may* define an attribute ``_inherit_decorators_`` which lists `OrderedDescriptor` classes that *should* be added from base classes. See the examples section below for an example of this. Examples -------- >>> from astropy.utils import OrderedDescriptor, OrderedDescriptorContainer >>> class TypedAttribute(OrderedDescriptor): ... \"\"\" ... Attributes that may only be assigned objects of a specific type, ... or subclasses thereof. For some reason we care about their order. ... \"\"\" ... ... _class_attribute_ = 'typed_attributes' ... _name_attribute_ = 'name' ... # A default name so that instances not attached to a class can ... # still be repr'd; useful for debugging ... name = '<unbound>' ... ... def __init__(self, type): ... # Make sure not to forget to call the super __init__ ... super().__init__() ... self.type = type ... ... def __get__(self, obj, objtype=None): ... if obj is None: ... return self ... if self.name in obj.__dict__: ... return obj.__dict__[self.name] ... else: ... raise AttributeError(self.name) ... ... def __set__(self, obj, value): ... if not isinstance(value, self.type): ... raise ValueError('{0}.{1} must be of type {2!r}'.format( ... obj.__class__.__name__, self.name, self.type)) ... obj.__dict__[self.name] = value ... ... def __delete__(self, obj): ... if self.name in obj.__dict__: ... del obj.__dict__[self.name] ... else: ... raise AttributeError(self.name) ... ... def __repr__(self): ... if isinstance(self.type, tuple) and len(self.type) > 1: ... typestr = '({0})'.format( ... ', '.join(t.__name__ for t in self.type)) ... else: ... typestr = self.type.__name__ ... return '<{0}(name={1}, type={2})>'.format( ... self.__class__.__name__, self.name, typestr) ... Now let's create an example class that uses this ``TypedAttribute``:: >>> class Point2D(metaclass=OrderedDescriptorContainer): ... x = TypedAttribute((float, int)) ... y = TypedAttribute((float, int)) ... ... def __init__(self, x, y): ... self.x, self.y = x, y ... >>> p1 = Point2D(1.0, 2.0) >>> p1.x 1.0 >>> p1.y 2.0 >>> p2 = Point2D('a', 'b') # doctest: +IGNORE_EXCEPTION_DETAIL Traceback (most recent call last): ... ValueError: Point2D.x must be of type (float, int>) We see that ``TypedAttribute`` works more or less as advertised, but there's nothing special about that. Let's see what `OrderedDescriptorContainer` did for us:: >>> Point2D.typed_attributes OrderedDict([('x', <TypedAttribute(name=x, type=(float, int))>), ('y', <TypedAttribute(name=y, type=(float, int))>)]) If we create a subclass, it does *not* by default add inherited descriptors to ``typed_attributes``:: >>> class Point3D(Point2D): ... z = TypedAttribute((float, int)) ... >>> Point3D.typed_attributes OrderedDict([('z', <TypedAttribute(name=z, type=(float, int))>)]) However, if we specify ``_inherit_descriptors_`` from ``Point2D`` then it will do so:: >>> class Point3D(Point2D): ... _inherit_descriptors_ = (TypedAttribute,) ... z = TypedAttribute((float, int)) ... >>> Point3D.typed_attributes OrderedDict([('x', <TypedAttribute(name=x, type=(float, int))>), ('y', <TypedAttribute(name=y, type=(float, int))>), ('z', <TypedAttribute(name=z, type=(float, int))>)]) .. note:: Hopefully it is clear from these examples that this construction also allows a class of type `OrderedDescriptorContainer` to use multiple different `OrderedDescriptor` classes simultaneously. """ _inherit_descriptors_ = () def __init__(cls, cls_name, bases, members): descriptors = defaultdict(list) seen = set() inherit_descriptors = () descr_bases = {} for mro_cls in cls.__mro__: for name, obj in mro_cls.__dict__.items(): if name in seen: # Checks if we've already seen an attribute of the given # name (if so it will override anything of the same name in # any base class) continue seen.add(name) if (not isinstance(obj, OrderedDescriptor) or (inherit_descriptors and not isinstance(obj, inherit_descriptors))): # The second condition applies when checking any # subclasses, to see if we can inherit any descriptors of # the given type from subclasses (by default inheritance is # disabled unless the class has _inherit_descriptors_ # defined) continue if obj._name_attribute_ is not None: setattr(obj, obj._name_attribute_, name) # Don't just use the descriptor's class directly; instead go # through its MRO and find the class on which _class_attribute_ # is defined directly. This way subclasses of some # OrderedDescriptor *may* override _class_attribute_ and have # its own _class_attribute_, but by default all subclasses of # some OrderedDescriptor are still grouped together # TODO: It might be worth clarifying this in the docs if obj.__class__ not in descr_bases: for obj_cls_base in obj.__class__.__mro__: if '_class_attribute_' in obj_cls_base.__dict__: descr_bases[obj.__class__] = obj_cls_base descriptors[obj_cls_base].append((obj, name)) break else: # Make sure to put obj first for sorting purposes obj_cls_base = descr_bases[obj.__class__] descriptors[obj_cls_base].append((obj, name)) if not getattr(mro_cls, '_inherit_descriptors_', False): # If _inherit_descriptors_ is undefined then we don't inherit # any OrderedDescriptors from any of the base classes, and # there's no reason to continue through the MRO break else: inherit_descriptors = mro_cls._inherit_descriptors_ for descriptor_cls, instances in descriptors.items(): instances.sort() instances = OrderedDict((key, value) for value, key in instances) setattr(cls, descriptor_cls._class_attribute_, instances) super(OrderedDescriptorContainer, cls).__init__(cls_name, bases, members)
def get_parameters(members): """ Looks for ordered descriptors in a class definition and copies such definitions in two new class attributes, one being a dictionary of these objects keyed by their attribute names, and the other a simple list of those names. """ pdict = OrderedDict() for name, obj in members.items(): if (not isinstance(obj, OrderedDescriptor)): continue if obj._name_attribute_ is not None: setattr(obj, '_name', name) pdict[name] = obj # members['_parameter_vals_'] = pdict members['_parameters_'] = pdict LOCALE_LOCK = threading.Lock() @contextmanager def _set_locale(name): """ Context manager to temporarily set the locale to ``name``. An example is setting locale to "C" so that the C strtod() function will use "." as the decimal point to enable consistent numerical string parsing. Note that one cannot nest multiple _set_locale() context manager statements as this causes a threading lock. This code taken from https://stackoverflow.com/questions/18593661/how-do-i-strftime-a-date-object-in-a-different-locale. Parameters ========== name : str Locale name, e.g. "C" or "fr_FR". """ name = str(name) with LOCALE_LOCK: saved = locale.setlocale(locale.LC_ALL) if saved == name: # Don't do anything if locale is already the requested locale yield else: try: locale.setlocale(locale.LC_ALL, name) yield finally: locale.setlocale(locale.LC_ALL, saved) set_locale = deprecated('4.0')(_set_locale) set_locale.__doc__ = """Deprecated version of :func:`_set_locale` above. See https://github.com/astropy/astropy/issues/9196 """
[docs]class ShapedLikeNDArray(metaclass=abc.ABCMeta): """Mixin class to provide shape-changing methods. The class proper is assumed to have some underlying data, which are arrays or array-like structures. It must define a ``shape`` property, which gives the shape of those data, as well as an ``_apply`` method that creates a new instance in which a `~numpy.ndarray` method has been applied to those. Furthermore, for consistency with `~numpy.ndarray`, it is recommended to define a setter for the ``shape`` property, which, like the `~numpy.ndarray.shape` property allows in-place reshaping the internal data (and, unlike the ``reshape`` method raises an exception if this is not possible). This class also defines default implementations for ``ndim`` and ``size`` properties, calculating those from the ``shape``. These can be overridden by subclasses if there are faster ways to obtain those numbers. """ # Note to developers: if new methods are added here, be sure to check that # they work properly with the classes that use this, such as Time and # BaseRepresentation, i.e., look at their ``_apply`` methods and add # relevant tests. This is particularly important for methods that imply # copies rather than views of data (see the special-case treatment of # 'flatten' in Time). @property @abc.abstractmethod def shape(self): """The shape of the underlying data.""" @abc.abstractmethod def _apply(method, *args, **kwargs): """Create a new instance, with ``method`` applied to underlying data. The method is any of the shape-changing methods for `~numpy.ndarray` (``reshape``, ``swapaxes``, etc.), as well as those picking particular elements (``__getitem__``, ``take``, etc.). It will be applied to the underlying arrays (e.g., ``jd1`` and ``jd2`` in `~astropy.time.Time`), with the results used to create a new instance. Parameters ---------- method : str Method to be applied to the instance's internal data arrays. args : tuple Any positional arguments for ``method``. kwargs : dict Any keyword arguments for ``method``. """ @property def ndim(self): """The number of dimensions of the instance and underlying arrays.""" return len(self.shape) @property def size(self): """The size of the object, as calculated from its shape.""" size = 1 for sh in self.shape: size *= sh return size @property def isscalar(self): return self.shape == () def __len__(self): if self.isscalar: raise TypeError("Scalar {!r} object has no len()" .format(self.__class__.__name__)) return self.shape[0] def __bool__(self): """Any instance should evaluate to True, except when it is empty.""" return self.size > 0 def __getitem__(self, item): try: return self._apply('__getitem__', item) except IndexError: if self.isscalar: raise TypeError('scalar {!r} object is not subscriptable.' .format(self.__class__.__name__)) else: raise def __iter__(self): if self.isscalar: raise TypeError('scalar {!r} object is not iterable.' .format(self.__class__.__name__)) # We cannot just write a generator here, since then the above error # would only be raised once we try to use the iterator, rather than # upon its definition using iter(self). def self_iter(): for idx in range(len(self)): yield self[idx] return self_iter()
[docs] def copy(self, *args, **kwargs): """Return an instance containing copies of the internal data. Parameters are as for :meth:`~numpy.ndarray.copy`. """ return self._apply('copy', *args, **kwargs)
[docs] def reshape(self, *args, **kwargs): """Returns an instance containing the same data with a new shape. Parameters are as for :meth:`~numpy.ndarray.reshape`. Note that it is not always possible to change the shape of an array without copying the data (see :func:`~numpy.reshape` documentation). If you want an error to be raise if the data is copied, you should assign the new shape to the shape attribute (note: this may not be implemented for all classes using ``ShapedLikeNDArray``). """ return self._apply('reshape', *args, **kwargs)
[docs] def ravel(self, *args, **kwargs): """Return an instance with the array collapsed into one dimension. Parameters are as for :meth:`~numpy.ndarray.ravel`. Note that it is not always possible to unravel an array without copying the data. If you want an error to be raise if the data is copied, you should should assign shape ``(-1,)`` to the shape attribute. """ return self._apply('ravel', *args, **kwargs)
[docs] def flatten(self, *args, **kwargs): """Return a copy with the array collapsed into one dimension. Parameters are as for :meth:`~numpy.ndarray.flatten`. """ return self._apply('flatten', *args, **kwargs)
[docs] def transpose(self, *args, **kwargs): """Return an instance with the data transposed. Parameters are as for :meth:`~numpy.ndarray.transpose`. All internal data are views of the data of the original. """ return self._apply('transpose', *args, **kwargs)
@property def T(self): """Return an instance with the data transposed. Parameters are as for :attr:`~numpy.ndarray.T`. All internal data are views of the data of the original. """ if self.ndim < 2: return self else: return self.transpose()
[docs] def swapaxes(self, *args, **kwargs): """Return an instance with the given axes interchanged. Parameters are as for :meth:`~numpy.ndarray.swapaxes`: ``axis1, axis2``. All internal data are views of the data of the original. """ return self._apply('swapaxes', *args, **kwargs)
[docs] def diagonal(self, *args, **kwargs): """Return an instance with the specified diagonals. Parameters are as for :meth:`~numpy.ndarray.diagonal`. All internal data are views of the data of the original. """ return self._apply('diagonal', *args, **kwargs)
[docs] def squeeze(self, *args, **kwargs): """Return an instance with single-dimensional shape entries removed Parameters are as for :meth:`~numpy.ndarray.squeeze`. All internal data are views of the data of the original. """ return self._apply('squeeze', *args, **kwargs)
[docs] def take(self, indices, axis=None, mode='raise'): """Return a new instance formed from the elements at the given indices. Parameters are as for :meth:`~numpy.ndarray.take`, except that, obviously, no output array can be given. """ return self._apply('take', indices, axis=axis, mode=mode)
[docs]class IncompatibleShapeError(ValueError): def __init__(self, shape_a, shape_a_idx, shape_b, shape_b_idx): super().__init__(shape_a, shape_a_idx, shape_b, shape_b_idx)
[docs]def check_broadcast(*shapes): """ Determines whether two or more Numpy arrays can be broadcast with each other based on their shape tuple alone. Parameters ---------- *shapes : tuple All shapes to include in the comparison. If only one shape is given it is passed through unmodified. If no shapes are given returns an empty `tuple`. Returns ------- broadcast : `tuple` If all shapes are mutually broadcastable, returns a tuple of the full broadcast shape. """ if len(shapes) == 0: return () elif len(shapes) == 1: return shapes[0] reversed_shapes = (reversed(shape) for shape in shapes) full_shape = [] for dims in zip_longest(*reversed_shapes, fillvalue=1): max_dim = 1 max_dim_idx = None for idx, dim in enumerate(dims): if dim == 1: continue if max_dim == 1: # The first dimension of size greater than 1 max_dim = dim max_dim_idx = idx elif dim != max_dim: raise IncompatibleShapeError( shapes[max_dim_idx], max_dim_idx, shapes[idx], idx) full_shape.append(max_dim) return tuple(full_shape[::-1])
[docs]def dtype_bytes_or_chars(dtype): """ Parse the number out of a dtype.str value like '<U5' or '<f8'. See #5819 for discussion on the need for this function for getting the number of characters corresponding to a string dtype. Parameters ---------- dtype : numpy dtype object Input dtype Returns ------- bytes_or_chars : int or None Bits (for numeric types) or characters (for string types) """ match = re.search(r'(\d+)$', dtype.str) out = int(match.group(1)) if match else None return out
[docs]def unbroadcast(array): """ Given an array, return a new array that is the smallest subset of the original array that can be re-broadcasted back to the original array. See https://stackoverflow.com/questions/40845769/un-broadcasting-numpy-arrays for more details. """ if array.ndim == 0: return array array = array[tuple((slice(0, 1) if stride == 0 else slice(None)) for stride in array.strides)] # Remove leading ones, which are not needed in numpy broadcasting. first_not_unity = next((i for (i, s) in enumerate(array.shape) if s > 1), array.ndim) return array.reshape(array.shape[first_not_unity:])
def pizza(): # pragma: no cover """ Open browser loaded with pizza options near you. *Disclaimers: Payments not included. Astropy is not responsible for any liability from using this function.* .. note:: Accuracy depends on your browser settings. """ import webbrowser webbrowser.open('https://www.google.com/search?q=pizza+near+me')