#! /usr/bin/env python
"""
utils - General tools of use to fileseq operations.
"""
from __future__ import absolute_import, division
from builtins import bytes
from builtins import next
from builtins import range
from builtins import object
import future.utils as futils
import decimal
from itertools import chain, count, islice
import os
import sys
from fileseq import exceptions
FILESYSTEM_ENCODING = sys.getfilesystemencoding() or 'utf-8'
[docs]def quantize(number, decimal_places, rounding=decimal.ROUND_HALF_EVEN):
"""
Round a decimal value to given number of decimal places
Args:
number (decimal.Decimal): Decimal number to round
decimal_places (int): Number of decimal places in return value
rounding (str): decimal.Decimal rounding mode. See rounding argument of
https://docs.python.org/2/library/decimal.html#decimal.Context
Returns:
decimal.Decimal:
"""
quantize_exponent = decimal.Decimal(1).scaleb(-decimal_places)
nq = number.quantize(quantize_exponent, rounding=rounding)
if nq.is_zero():
return nq.copy_abs()
return nq
[docs]def lenRange(start, stop, step=1):
"""
Get the length of values for a given range, exclusive of the stop
Args:
start (int):
stop (int):
step (int):
"""
if not step:
raise ValueError('step argument must not be zero')
if step > 0:
result = (stop - start + step - 1) // step
else:
result = (stop - start + step + 1) // step
return max(0, result)
[docs]class xrange2(object):
"""
An itertools-based replacement for xrange which does
not exhibit the OverflowError issue on some platforms,
when a value exceeds a C long size.
Provides the features of an islice, with the added support
for checking the length of the range.
"""
__slots__ = ['_len', '_islice', '_start', '_stop', '_step']
def __init__(self, start, stop=None, step=1):
if stop is None:
start, stop = 0, start
self._len = lenRange(start, stop, step)
self._islice = islice(count(start, step), self._len)
self._start = start
self._stop = stop
self._step = step
def __repr__(self):
if self._step == 1:
return 'range({}, {})'.format(self._start, self._stop)
else:
return 'range({}, {}, {})'.format(self._start, self._stop, self._step)
def __len__(self):
return self._len
def __next__(self):
return next(self._islice)
def __iter__(self):
return self._islice.__iter__()
@property
def start(self):
return self._start
@property
def stop(self):
return self._stop
@property
def step(self):
return self._step
# Issue #44
# On Windows platform, it is possible for xrange to get an
# OverflowError if a value passed to xrange exceeds the size of a C long.
# Switch to an alternate implementation.
if os.name == 'nt':
xrange = range = xrange2
else:
xrange = range
class _islice(object):
def __init__(self, gen, start, stop, step=1):
self._gen = gen
self._start = start
self._stop = stop
self._step = step
def __len__(self):
return lenRange(self._start, self._stop, self._step)
def __next__(self):
return next(self._gen)
def __iter__(self):
return self._gen.__iter__()
@property
def start(self):
return self._start
@property
def stop(self):
return self._stop
@property
def step(self):
return self._step
class _xfrange(_islice):
def __len__(self):
stop = self._stop + (1 if self._start <= self._stop else -1)
return lenRange(self._start, stop, self._step)
[docs]def xfrange(start, stop, step=1, maxSize=-1):
"""
Returns a generator that yields the frames from start to stop, inclusive.
In other words it adds or subtracts a frame, as necessary, to return the
stop value as well, if the stepped range would touch that value.
Args:
start (int):
stop (int):
step (int): Note that the sign will be ignored
maxSize (int):
Returns:
generator:
Raises:
:class:`fileseq.exceptions.MaxSizeException`: if size is exceeded
"""
if not step:
raise ValueError('xfrange() step argument must not be zero')
start, stop, step = normalizeFrames([start, stop, step])
if start <= stop:
step = abs(step)
else:
step = -abs(step)
if isinstance(start, futils.integer_types):
size = (stop - start) // step + 1
else:
size = int((stop - start) / step) + 1
if maxSize >= 0 and size > maxSize:
raise exceptions.MaxSizeException(
"Size %d > %s (MAX_FRAME_SIZE)" % (size, maxSize))
# because an xrange is an odd object all its own, we wrap it in a
# generator expression to get a proper Generator
if isinstance(start, futils.integer_types):
offset = step // abs(step)
gen = (f for f in range(start, stop + offset, step))
else:
gen = (start + i * step for i in range(size))
return _xfrange(gen, start, stop, step)
[docs]def batchFrames(start, stop, batch_size):
"""
Returns a generator that yields batches of frames from start to stop, inclusive.
Each batch value is a ``range`` generator object, also providing start, stop, and
step properties.
The last batch frame length may be smaller if the batches cannot be divided evenly.
start value is allowed to be greater than stop value, to generate decreasing frame
values.
Args:
start (int): start frame value
stop (int): stop frame value
batch_size (int): max size of each batch
Yields:
range(sub_start, sub_stop)
"""
if batch_size <= 0:
return
for i in xfrange(start, stop, batch_size):
if start <= stop:
sub_stop = min(i - 1 + batch_size, stop)
else:
sub_stop = max(i + 1 - batch_size, stop)
yield xfrange(i, sub_stop)
[docs]def batchIterable(it, batch_size):
"""
Returns a generator that yields batches of items returned by the given iterable.
The last batch frame length may be smaller if the batches cannot be divided evenly.
Args:
it (iterable): An iterable from which to yield batches of values
batch_size (int): max size of each batch
Yields:
iterable: a subset of batched items
"""
if batch_size <= 0:
return
# Try to get the length. If it is a generator with no
# known length, then we have to use a less efficient
# method that builds results by exhausting the generator
try:
length = len(it)
except TypeError:
for b in _batchGenerator(it, batch_size):
yield b
return
# We can use the known length to yield slices
for start in xrange(0, length, batch_size):
stop = start + batch_size
gen = islice(it, start, stop)
yield _islice(gen, start, stop)
def _batchGenerator(gen, batch_size):
"""
A batching generator function that handles a generator
type, where the length isn't known.
Args:
gen: generator object
batch_size (int): max size of each batch
Yields:
iterable: a subset of batched items
"""
batch = []
for item in gen:
batch.append(item)
if len(batch) == batch_size:
yield batch
batch = []
if batch:
yield batch
[docs]def normalizeFrame(frame):
"""
Convert a frame number to the most appropriate type - the most compact type
that doesn't affect precision, for example numbers that convert exactly
to integer values will be converted to int
Args:
frame (int, float, decimal.Decimal, str): frame number to normalize
Returns:
frame (int, float, or decimal.Decimal):
"""
if frame is None:
return None
elif isinstance(frame, futils.integer_types):
return frame
elif isinstance(frame, float):
frame_int = int(frame)
if frame == frame_int:
return frame_int
return frame
elif isinstance(frame, decimal.Decimal):
frame_int = int(frame)
if frame == frame_int:
return frame_int
return frame.normalize()
else:
try:
return int(frame)
except ValueError:
try:
frame = decimal.Decimal(frame)
except decimal.DecimalException:
return frame
else:
return normalizeFrame(frame)
[docs]def normalizeFrames(frames):
"""
Convert a sequence of frame numbers to the most appropriate type for the
overall sequence, where all members of the result are of the same type.
Args:
frames (iterable of int, float, decimal.Decimal, or str):
frame numbers to normalize
Returns:
frames (iterable of int, float, or decimal.Decimal):
"""
# Normalise all frame values and find their type
frames = [normalizeFrame(frame) for frame in frames]
frame_types = set(type(frame) for frame in frames)
# Determine best overall type for frames
if float in frame_types:
FrameType = float
elif decimal.Decimal in frame_types:
FrameType = decimal.Decimal
else:
FrameType = int
if len(frame_types) == 1:
return frames
# Convert all frames to chosen type
frames = [FrameType(frame) for frame in frames]
# Ensure all decimal frames have same exponent
if FrameType is decimal.Decimal:
maximum_decimal_places = max(
-frame.as_tuple().exponent for frame in frames
)
frames = [quantize(frame, maximum_decimal_places) for frame in frames]
return frames
[docs]def unique(seen, *iterables):
"""
Get the unique items in iterables while preserving order. Note that this
mutates the seen set provided only when the returned generator is used.
Args:
seen (set): either an empty set, or the set of things already seen
*iterables: one or more iterable lists to chain together
Returns:
generator:
"""
_add = seen.add
# return a generator of the unique items and the set of the seen items
# the seen set will mutate when the generator is iterated over
return (i for i in chain(*iterables) if i not in seen and not _add(i))
[docs]def pad(number, width=0, decimal_places=None):
"""
Return the zero-padded string of a given number.
Args:
number (str, int, float, or decimal.Decimal): the number to pad
width (int): width for zero padding the integral component
decimal_places (int): number of decimal places to use in frame range
Returns:
str:
"""
# Make the common case fast. Truncate to integer value as USD does.
# https://graphics.pixar.com/usd/docs/api/_usd__page__value_clips.html
# See _DeriveClipTimeString for formating of templateAssetPath
# https://github.com/PixarAnimationStudios/USD/blob/release/pxr/usd/usd/clipSetDefinition.cpp
if decimal_places == 0:
try:
number = round(number) or 0
except TypeError:
pass
return futils.native_str(number).partition(".")[0].zfill(width)
# USD ultimately uses vsnprintf to format floats for templateAssetPath:
# _DeriveClipTimeString -> TfStringPrintf -> ArchVStringPrintf -> ArchVsnprintf -> vsnprintf
# Since glibc 2.17 the printf family of functions rounds floats using the
# current IEEE rounding mode, by default bankers' rounding (FE_TONEAREST).
# See https://sourceware.org/bugzilla/show_bug.cgi?id=5044 and man(3) fegetround
# Also https://www.exploringbinary.com/inconsistent-rounding-of-printed-floating-point-numbers/
if decimal_places is not None:
if not isinstance(number, decimal.Decimal):
number = decimal.Decimal(number)
number = quantize(number, decimal_places, decimal.ROUND_HALF_EVEN)
number = futils.native_str(number)
parts = number.split(".", 1)
parts[0] = parts[0].zfill(width)
return ".".join(parts)
def _getPathSep(path):
"""
Abstracts returning the appropriate path separator
for the given path string.
This implementation always returns ``os.sep``
Abstracted to make test mocking easier.
Args:
path (str): A path to check for the most common sep
Returns:
str:
"""
return os.sep
_STR_TYPES = frozenset((futils.text_type, futils.binary_type))
[docs]def asString(obj):
"""
Ensure an object is either explicitly str or unicode
and not some derived type that can change semantics.
If the object is unicode, return unicode.
Otherwise return the string conversion of the object.
Args:
obj: Object to return as str or unicode
Returns:
str or unicode:
"""
typ = type(obj)
# explicit type check as faster path
if typ in _STR_TYPES:
if not futils.PY2 and typ is futils.binary_type:
obj = os.fsdecode(obj)
return obj
# derived type check
elif isinstance(obj, bytes):
if futils.PY2:
obj = bytes(obj)
else:
obj = obj.decode(FILESYSTEM_ENCODING)
else:
obj = futils.text_type(obj)
return futils.native(obj)
