# 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 contextlib
import difflib
import inspect
import json
import locale
import os
import re
import signal
import sys
import threading
import traceback
import unicodedata
from contextlib import contextmanager
from astropy.utils import deprecated
__all__ = [
"isiterable",
"silence",
"format_exception",
"NumpyRNGContext",
"find_api_page",
"is_path_hidden",
"walk_skip_hidden",
"JsonCustomEncoder",
"indent",
"dtype_bytes_or_chars",
]
NOT_OVERWRITING_MSG = (
"File {} already exists. If you mean to replace it "
'then use the argument "overwrite=True".'
)
# A useful regex for tests.
_NOT_OVERWRITING_MSG_MATCH = (
r"File .* already exists\. If you mean to "
r"replace it then use the argument "
r'"overwrite=True"\.'
)
[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]
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
from zlib import decompress
from astropy.utils.data import get_readable_fileobj
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
url = baseurl + "objects.inv"
headers = {"User-Agent": f"Astropy/{version}"}
with get_readable_fileobj(
url, encoding="binary", remote_timeout=timeout, http_headers=headers
) as uf:
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(
f"The file downloaded from {baseurl}objects.inv does not seem to be"
"the usual Sphinx objects.inv format. Maybe it "
"has changed?"
)
compressed = oiread[(idx + 1) :]
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 = {
k: v for v, k in signal.__dict__.items() if v.startswith("SIG")
}
return signal_to_name_map.get(signum, "UNKNOWN")
# _has_hidden_attribute() can be deleted together with deprecated is_path_hidden() and
# walk_skip_hidden().
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]
@deprecated(since="6.0")
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]
@deprecated(since="6.0")
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):
import numpy as np
from astropy import units as u
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 ""
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)
[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
def _hungry_for(option): # pragma: no cover
"""
Open browser loaded with ``option`` 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(f"https://www.google.com/search?q={option}+near+me")
def pizza(): # pragma: no cover
"""``/pizza``."""
_hungry_for("pizza")
def coffee(is_adam=False, is_brigitta=False): # pragma: no cover
"""``/coffee``."""
if is_adam and is_brigitta:
raise ValueError("There can be only one!")
if is_adam:
option = "fresh+third+wave+coffee"
elif is_brigitta:
option = "decent+espresso"
else:
option = "coffee"
_hungry_for(option)
