#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""
Common Utilities
================
Defines common utilities objects that don't fall in any specific category.
"""
from __future__ import division, unicode_literals
import numpy as np
import os
import re
from collections import defaultdict
__author__ = 'Colour Developers'
__copyright__ = 'Copyright (C) 2015-2016 - Colour Developers'
__license__ = 'New BSD License - http://opensource.org/licenses/BSD-3-Clause'
__maintainer__ = 'Colour Developers'
__email__ = 'colour-science@googlegroups.com'
__status__ = 'Production'
__all__ = ['linear_conversion',
'vivification',
'vivified_to_dict',
'path_exists',
'filter_files']
[docs]def linear_conversion(a, old_range, new_range):
"""
Performs a simple linear conversion of given array between the old and new
ranges.
Parameters
----------
a : array_like
Array to perform the linear conversion onto.
old_range : array_like
Old range.
new_range : array_like
New range.
Returns
-------
ndarray
Examples
--------
>>> a = np.linspace(0, 1, 10)
>>> linear_conversion(a, np.array([0, 1]), np.array([1, 10]))
array([ 1., 2., 3., 4., 5., 6., 7., 8., 9., 10.])
"""
a = np.asarray(a)
in_min, in_max = old_range
out_min, out_max = new_range
return (((a - in_min) / (in_max - in_min)) *
(out_max - out_min) + out_min)
[docs]def vivification():
"""
Implements supports for vivification of the underlying dict like
data-structure, magical!
Returns
-------
defaultdict
Examples
--------
>>> vivified = vivification()
>>> vivified['my']['attribute'] = 1
>>> vivified['my'] # doctest: +ELLIPSIS
defaultdict(<function vivification at 0x...>, {u'attribute': 1})
>>> vivified['my']['attribute']
1
"""
return defaultdict(vivification)
[docs]def vivified_to_dict(vivified):
"""
Converts given vivified data-structure to dictionary.
Parameters
----------
vivified : defaultdict
Vivified data-structure.
Returns
-------
dict
Examples
--------
>>> vivified = vivification()
>>> vivified['my']['attribute'] = 1
>>> vivified_to_dict(vivified)
{u'my': {u'attribute': 1}}
"""
if isinstance(vivified, defaultdict):
vivified = {key: vivified_to_dict(value)
for key, value in vivified.iteritems()}
return vivified
[docs]def path_exists(path):
"""
Returns if given path exists.
Parameters
----------
path : unicode
Path to check the existence.
Returns
-------
bool
Examples
--------
>>> path_exists(__file__)
True
>>> path_exists('')
False
"""
if not path:
return False
else:
return os.path.exists(path)
[docs]def filter_files(directory, extensions):
"""
Filters given directory for files matching given extensions.
Parameters
----------
directory : unicode
Directory to filter.
extensions : tuple or list
Extensions to filter on.
Returns
-------
list
Filtered files.
"""
return map(lambda x: os.path.join(directory, x),
filter(lambda x: re.search('\.({0})$'.format(
'|'.join(extensions)), x), sorted(os.listdir(directory))))