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# -*- coding: utf-8 -*- 

 

u'''Basic constants, definitions and functions. 

 

''' 

from pygeodesy.lazily import _ALL_LAZY 

 

from copy import copy as _copy, deepcopy as _deepcopy 

from inspect import isclass 

from math import copysign, isinf, isnan 

from sys import float_info as _float_info 

 

# all public contants, classes and functions 

__all__ = _ALL_LAZY.basics 

__version__ = '20.03.23' 

 

try: # Luciano Ramalho, "Fluent Python", page 395, O'Reilly, 2016 

from numbers import Integral as _Ints #: (INTERNAL) Int objects 

except ImportError: # PYCHOK no cover 

try: # _Ints imported by .utily 

_Ints = int, long #: (INTERNAL) Int objects (C{tuple}) 

except NameError: # Python 3+ 

_Ints = int, #: (INTERNAL) Int objects (C{tuple}) 

 

try: # similarly ... 

from numbers import Real as _Scalars #: (INTERNAL) Scalar objects 

except ImportError: # PYCHOK no cover 

try: 

_Scalars = int, long, float #: (INTERNAL) Scalar objects (C{tuple}) 

except NameError: 

_Scalars = int, float #: (INTERNAL) Scalar objects (C{tuple}) 

 

try: 

try: # use C{from collections.abc import ...} in Python 3.9+ 

from collections.abc import Sequence as _Sequence # imported by .points 

except ImportError: # no .abc in Python 2.7- 

from collections import Sequence as _Sequence # imported by .points 

if isinstance([], _Sequence) and isinstance((), _Sequence): 

# and isinstance(range(1), _Sequence): 

_Seqs = _Sequence 

else: 

raise ImportError # AssertionError 

except ImportError: # PYCHOK no cover 

_Sequence = tuple # immutable for .points._Basequence 

_Seqs = list, _Sequence # , range for function len2 below 

 

try: 

_Strs = basestring, str 

except NameError: # Python 3+ 

_Strs = str, 

 

try: 

EPS = _float_info.epsilon #: System's epsilon (C{float}) 

MANTIS = _float_info.mant_dig #: System's mantissa bits (C{int}) 

MAX = _float_info.max #: System's float max (C{float}) 

MIN = _float_info.min #: System's float min (C{float}) 

except AttributeError: # PYCHOK no cover 

EPS = 2.220446049250313e-16 #: Epsilon (C{float}) 2**-52? 

MANTIS = 53 #: Mantissa bits ≈53 (C{int}) 

MAX = pow(2.0, 1023) * (2 - EPS) #: Float max (C{float}) ≈10**308, 2**1024? 

MIN = pow(2.0, -1021) # Float min (C{float}) ≈10**-308, 2**-1021? 

EPS_2 = EPS / 2.0 #: M{EPS / 2} ≈1.110223024625e-16 (C{float}) 

EPS1 = 1.0 - EPS #: M{1 - EPS} ≈0.9999999999999998 (C{float}) 

EPS1_2 = 1.0 - EPS_2 #: M{1 - EPS_2} ≈0.9999999999999999 (C{float}) 

# _1EPS = 1.0 + EPS #: M{1 + EPS} ≈1.0000000000000002 (C{float}) 

 

INF = float('inf') #: Infinity (C{float}), see function C{isinf}, C{isfinite} 

NAN = float('nan') #: Not-A-Number (C{float}), see function C{isnan} 

NEG0 = -0.0 #: Negative 0.0 (C{float}), see function C{isneg0} 

 

OK = 'OK' # OK for test like I{if ... is OK: ...} 

 

# R_M moved here to avoid circular imports 

R_M = 6371008.771415 #: Mean, spherical earth radius (C{meter}). 

 

_limiterrors = True # imported by .formy 

_MISSING = object() # singleton, imported by .wgrs 

 

 

class LenError(ValueError): 

'''Error raised for mis-matching C{len} values. 

''' 

def __init__(self, where, **lens): # Error=ValueError 

'''New L{LenError}. 

 

@arg where: Object with C{.__name__} attribute (C{class}, C{method}, or C{function}). 

@kwarg lens: Two or more C{name=len(name)} pairs (C{keyword arguments}). 

''' 

ns, vs = zip(*sorted(lens.items())) 

ns = ', '.join(ns) 

vs = ' vs '.join(map(str, vs)) 

t = where.__name__, ns, 'len', vs 

ValueError.__init__(self, '%s(%s) %s: %s' % t) 

 

 

class LimitError(ValueError): 

'''Error raised for lat- or longitudinal deltas exceeding 

the B{C{limit}} in functions L{equirectangular} and 

L{equirectangular_} and C{nearestOn*} and C{simplify*} 

functions or methods. 

''' 

pass 

 

 

def clips(bstr, limit=50, white=''): 

'''Clip a string to the given length limit. 

 

@arg bstr: String (C{bytes} or C{str}). 

@kwarg limit: Length limit (C{int}). 

@kwarg white: Whitespace replacement (C{str}). 

 

@return: Un-/clipped B{C{bstr}}. 

''' 

if len(bstr) > limit > 8: 

h = limit // 2 

bstr = bstr[:h] + type(bstr)('....') + bstr[-h:] 

if white: # replace whitespace 

bstr = type(bstr)(white).join(bstr.split()) 

return bstr 

 

 

def halfs2(str2): 

'''Split a string in 2 halfs. 

 

@arg str2: String to split (C{str}). 

 

@return: 2-Tuple (1st, 2nd) half (C{str}). 

 

@raise ValueError: Zero or odd C{len}(B{str2}). 

''' 

h, r = divmod(len(str2), 2) 

if r or not h: 

raise ValueError('%s invalid: %r' % ('str2', str2)) 

return str2[:h], str2[h:] 

 

 

try: 

from math import isfinite # new in Python 3+ 

except ImportError: 

 

def isfinite(obj): 

'''Check for C{Inf} and C{NaN} values. 

 

@arg obj: Value (C{scalar}). 

 

@return: C{False} if B{C{obj}} is C{INF} or C{NAN}, 

C{True} otherwise. 

 

@raise TypeError: Non-scalar B{C{obj}}. 

''' 

if not isscalar(obj): 

raise _isnotError(isscalar.__name__, obj=obj) 

return not (isinf(obj) or isnan(obj)) 

 

 

def isint(obj, both=False): 

'''Check for integer type or an integer C{float}. 

 

@arg obj: The object (any C{type}). 

@kwarg both: Optionally, check both type and value (C{bool}). 

 

@return: C{True} if B{C{obj}} is C{int}, C{False} otherwise. 

''' 

if both and isinstance(obj, float): # NOT _Scalars! 

try: 

return obj.is_integer() 

except AttributeError: 

return False # XXX float(int(obj)) == obj? 

return isinstance(obj, _Ints) 

 

 

def isneg0(obj): 

'''Check for L{NEG0}, negative 0.0. 

 

@arg obj: Value (C{scalar}). 

 

@return: C{True} if B{C{obj}} is C{NEG0} or -0.0, 

C{False} otherwise. 

''' 

return obj in (0.0, NEG0) and copysign(1, obj) < 0 

# and str(obj).rstrip('0') == '-0.' 

 

 

def _isnotError(*names, **pair): # Error=TypeError, name=value 

'''(INTERNAL) Format a C{TypeError} for a C{name=value} pair. 

''' 

Error = pair.pop('Error', TypeError) 

for n, v in pair.items(): 

break 

else: 

n, v = 'pair', 'N/A' 

t = ' or ' .join(names) 

return Error('%s not %s: %r' % (n, t, v)) 

 

 

def isscalar(obj): 

'''Check for scalar types. 

 

@arg obj: The object (any C{type}). 

 

@return: C{True} if B{C{obj}} is C{scalar}, C{False} otherwise. 

''' 

return isinstance(obj, _Scalars) 

 

 

def issequence(obj, *excluded): 

'''Check for sequence types. 

 

@arg obj: The object (any C{type}). 

@arg excluded: Optional, exclusions (C{type}). 

 

@note: Excluding C{tuple} implies excluding C{namedtuple}. 

 

@return: C{True} if B{C{obj}} is a sequence, C{False} otherwise. 

''' 

if excluded: 

return isinstance(obj, _Seqs) and not \ 

isinstance(obj, excluded) 

else: 

return isinstance(obj, _Seqs) 

 

 

def isstr(obj): 

'''Check for string types. 

 

@arg obj: The object (any C{type}). 

 

@return: C{True} if B{C{obj}} is C{str}, C{False} otherwise. 

''' 

return isinstance(obj, _Strs) 

 

 

def issubclassof(sub, sup): 

'''Check whether a class is a subclass of a super class. 

 

@arg sub: The subclass (C{class}). 

@arg sup: The super class (C{class}). 

 

@return: C{True} if B{C{sub}} is a subclass of B{C{sup}}. 

''' 

return isclass(sub) and isclass(sup) and issubclass(sub, sup) 

 

 

def len2(items): 

'''Make built-in function L{len} work for generators, iterators, 

etc. since those can only be started exactly once. 

 

@arg items: Generator, iterator, list, range, tuple, etc. 

 

@return: 2-Tuple C{(n, items)} of the number of items (C{int}) 

and the items (C{list} or C{tuple}). 

''' 

if not isinstance(items, _Seqs): # NOT hasattr(items, '__len__'): 

items = list(items) 

return len(items), items 

 

 

def limiterrors(raiser=None): 

'''Get/set the raising of limit errors. 

 

@kwarg raiser: Choose C{True} to throw or C{False} to 

ignore L{LimitError} exceptions. Use 

C{None} to leave the setting unchanged. 

 

@return: Previous setting (C{bool}). 

''' 

global _limiterrors 

t = _limiterrors 

if raiser in (True, False): 

_limiterrors = raiser 

return t 

 

 

def map1(func, *xs): # XXX map_ 

'''Apply each argument to a single-argument function and 

return a C{tuple} of results. 

 

@arg func: Function to apply (C{callable}). 

@arg xs: Arguments to apply (C{any positional}). 

 

@return: Function results (C{tuple}). 

''' 

return tuple(map(func, xs)) 

 

 

def map2(func, *xs): 

'''Apply arguments to a function and return a C{tuple} of results. 

 

Unlike Python 2's built-in L{map}, Python 3+ L{map} returns a 

L{map} object, an iterator-like object which generates the 

results only once. Converting the L{map} object to a tuple 

maintains Python 2 behavior. 

 

@arg func: Function to apply (C{callable}). 

@arg xs: Arguments to apply (C{list, tuple, ...}). 

 

@return: Function results (C{tuple}). 

''' 

return tuple(map(func, *xs)) 

 

 

def property_doc_(doc): 

'''Decorator for a property with documentation. 

 

@arg doc: The property documentation (C{str}). 

 

@example: 

 

>>> @property_doc_("documentation text.") 

>>> def name(self): 

>>> ... 

>>> 

>>> @name.setter 

>>> def name(self, value): 

>>> ... 

''' 

# See Luciano Ramalho, "Fluent Python", page 212ff, O'Reilly, 2016, 

# "Parameterized Decorators", especially Example 7-23. Also, see 

# <https://Python-3-Patterns-Idioms-Test.ReadTheDocs.io/en/latest/PythonDecorators.html> 

 

def _property(method): 

'''(INTERNAL) Return C{method} as documented C{property.getter}. 

''' 

t = 'get and set' if doc.startswith(' ') else '' 

return property(method, None, None, 'Property to ' + t + doc) 

 

return _property 

 

 

class property_RO(property): 

# No __doc__ on purpose 

 

def __init__(self, method): # PYCHOK signature 

'''New immutable, read-only L{property_RO}. 

 

@arg method: The callable to be decorated as C{property.getter}. 

 

@note: Like standard Python C{property} without a C{property.setter}, 

but with a more descriptive error message when set. 

''' 

# U{Descriptor HowTo Guide<https://docs.Python.org/3/howto/descriptor.html>} 

def immutable(inst, value): 

'''Throws an C{AttributeError}, always. 

''' 

t = immutable.__name__, inst, method.__name__, value 

raise AttributeError('%s property: %r.%s = %r' % t) 

 

property.__init__(self, method, immutable, None, method.__doc__ or 'N/A') 

 

 

# def property_RO(method): # OBSOLETE 

# '''An immutable property (C{Read Only}). 

# 

# @arg method: The callable to be decorated as C{property.getter}. 

# 

# @note: Like standard Python C{property} without a C{property.setter}, 

# but with a more descriptive error message when set. 

# ''' 

# def Read_Only(inst, value): 

# '''Throws an C{AttributeError}, always. 

# ''' 

# t = Read_Only.__name__, inst, method.__name__, value 

# raise AttributeError('%s property: %r.%s = %r' % t) 

# 

# return property(method, Read_Only, None, method.__doc__ or 'N/A') 

 

 

def scalar(value, low=EPS, high=1.0, name='scalar', Error=ValueError): 

'''Validate a scalar. 

 

@arg value: The value (C{scalar}). 

@kwarg low: Optional lower bound (C{scalar}). 

@kwarg high: Optional upper bound (C{scalar}). 

@kwarg name: Optional name of value (C{str}). 

@kwarg Error: Exception to raise (C{ValueError}). 

 

@return: New value (C{type} of B{C{low}}). 

 

@raise TypeError: Non-scalar B{C{value}}. 

 

@raise Error: Out-of-bounds B{C{value}}. 

''' 

if not isscalar(value): 

raise _isnotError(scalar.__name__, **{name: value}) 

try: 

if low is None: 

v = float(value) 

else: 

v = type(low)(value) 

if low > v or v > high: 

raise ValueError 

except (TypeError, ValueError): 

raise _isnotError('valid', Error=Error, **{name: value}) 

return v 

 

 

def splice(iterable, n=2, fill=_MISSING): 

'''Split an iterable into C{n} slices. 

 

@arg iterable: Items to be spliced (C{list}, C{tuple}, ...). 

@kwarg n: Number of slices to generate (C{int}). 

@kwarg fill: Fill value for missing items. 

 

@return: Generator of B{C{n}} slices M{iterable[i::n] for i=0..n}. 

 

@note: Each generated slice is a C{tuple} or a C{list}, 

the latter only if the B{C{iterable}} is a C{list}. 

 

@raise ValueError: Non-C{int} or non-positive B{C{n}}. 

 

@example: 

 

>>> from pygeodesy import splice 

 

>>> a, b = splice(range(10)) 

>>> a, b 

((0, 2, 4, 6, 8), (1, 3, 5, 7, 9)) 

 

>>> a, b, c = splice(range(10), n=3) 

>>> a, b, c 

((0, 3, 6, 9), (1, 4, 7], [2, 5, 8)) 

 

>>> a, b, c = splice(range(10), n=3, fill=-1) 

>>> a, b, c 

((0, 3, 6, 9), (1, 4, 7, -1), (2, 5, 8, -1)) 

 

>>> list(splice(range(12), n=5)) 

[(0, 5, 10), (1, 6, 11), (2, 7), (3, 8), (4, 9)] 

 

>>> splice(range(9), n=1) 

<generator object splice at 0x0...> 

''' 

if not (isinstance(n, _Ints) and n > 0): 

raise ValueError('%s %s=%s' % ('splice', 'n', n)) 

 

t = iterable 

if not isinstance(t, (list, tuple)): 

t = tuple(t) # force tuple, also for PyPy3 

if n > 1: 

if fill is not _MISSING: 

m = len(t) % n 

if m > 0: # fill with same type 

t += type(t)((fill,)) * (n - m) 

for i in range(n): 

yield t[i::n] # [i:None:n] pychok -Tb ... 

else: 

yield t 

 

 

def _TypeError(*Types, **pairs): 

'''(INTERNAL) Check C{Types} of all C{name=value} pairs. 

''' 

for n, v in pairs.items(): 

if not isinstance(v, Types): 

t = ' or '.join(t.__name__ for t in Types) 

# first letter of Type name I{pronounced} as vowel 

a = 'an' if t[:1].lower() in 'aeinoux' else 'a' 

raise TypeError('%s not %s %s: %r' % (n, a, t, v)) 

 

 

def _xcopy(inst, deep=False): 

'''(INTERNAL) Copy an instance, shallow or deep. 

 

@arg inst: The instance to copy (C{_Named}). 

@kwarg deep: If C{True} make a deep, otherwise 

shallow copy (C{bool}). 

 

@return: The copy (C{This class} or subclass thereof). 

''' 

return _deepcopy(inst) if deep else _copy(inst) 

 

 

def _xkwds(kwds, **dflts): 

'''(INTERNAL) Override C{dflts} with C{kwds}. 

''' 

d = dflts 

if kwds: 

d = d.copy() 

d.update(kwds) 

return d 

 

# **) MIT License 

# 

# Copyright (C) 2016-2020 -- mrJean1 at Gmail -- All Rights Reserved. 

# 

# Permission is hereby granted, free of charge, to any person obtaining a 

# copy of this software and associated documentation files (the "Software"), 

# to deal in the Software without restriction, including without limitation 

# the rights to use, copy, modify, merge, publish, distribute, sublicense, 

# and/or sell copies of the Software, and to permit persons to whom the 

# Software is furnished to do so, subject to the following conditions: 

# 

# The above copyright notice and this permission notice shall be included 

# in all copies or substantial portions of the Software. 

# 

# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS 

# OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 

# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL 

# THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR 

# OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, 

# ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR 

# OTHER DEALINGS IN THE SOFTWARE.