--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/pyams_utils/list.py Wed Dec 05 12:45:56 2018 +0100
@@ -0,0 +1,125 @@
+#
+# Copyright (c) 2008-2015 Thierry Florac <tflorac AT ulthar.net>
+# All Rights Reserved.
+#
+# This software is subject to the provisions of the Zope Public License,
+# Version 2.1 (ZPL). A copy of the ZPL should accompany this distribution.
+# THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
+# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
+# FOR A PARTICULAR PURPOSE.
+#
+
+__docformat__ = 'restructuredtext'
+
+
+# import standard library
+from itertools import filterfalse
+from random import random, shuffle
+
+# import interfaces
+
+# import packages
+
+
+def unique(seq, key=None):
+ """Extract unique values from list, preserving order
+
+ :param iterator seq: input list
+ :param callable key: an identity function which is used to get 'identity' value of each element
+ in the list
+ :return: list; a new list containing only unique elements of the original list in their initial order.
+ Original list is not modified.
+
+ >>> from pyams_utils.list import unique
+ >>> mylist = [1, 2, 3, 2, 1]
+ >>> unique(mylist)
+ [1, 2, 3]
+
+ >>> mylist = [3, 2, 2, 1, 4, 2]
+ >>> unique(mylist)
+ [3, 2, 1, 4]
+
+ You can also set an 'id' function applied on each element:
+
+ >>> mylist = [1, 2, 3, '2', 4]
+ >>> unique(mylist, key=str)
+ [1, 2, 3, 4]
+ >>> mylist = ['A', 'B', 'b', '2', 4]
+ >>> unique(mylist, key=lambda x: str(x).lower())
+ ['A', 'B', '2', 4]
+ """
+ seen = set()
+ seen_add = seen.add
+ result = []
+ if key is None:
+ for element in filterfalse(seen.__contains__, seq):
+ seen_add(element)
+ result.append(element)
+ else:
+ for element in seq:
+ k = key(element)
+ if k not in seen:
+ seen_add(k)
+ result.append(element)
+ return result
+
+
+def unique_iter(iterable, key=None):
+ """Iterate over iterator values, yielding only unique values
+
+ :param iterator iterable: input iterator
+ :param callable key: an identity function which is used to get 'identity' value of each element
+ in the list
+ :return: an iterator of unique values
+
+ >>> from pyams_utils.list import unique_iter
+ >>> mylist = [1, 2, 3, 2, 1]
+ >>> list(unique_iter(mylist))
+ [1, 2, 3]
+
+ >>> mylist = [3, 2, 2, 1, 4, 2]
+ >>> list(unique_iter(mylist))
+ [3, 2, 1, 4]
+
+ You can also set an 'id' function applied on each element:
+
+ >>> mylist = [1, 2, 3, '2', 4]
+ >>> list(unique_iter(mylist, key=str))
+ [1, 2, 3, 4]
+ >>> mylist = ['A', 'B', 'b', '2', 4]
+ >>> list(unique_iter(mylist, key=lambda x: str(x).lower()))
+ ['A', 'B', '2', 4]
+ """
+ seen = set()
+ seen_add = seen.add
+ if key is None:
+ for element in filterfalse(seen.__contains__, iterable):
+ seen_add(element)
+ yield element
+ else:
+ for element in iterable:
+ k = key(element)
+ if k not in seen:
+ seen_add(k)
+ yield element
+
+
+def random_iter(iterable, limit=1):
+ """Get items randomly from an iterator
+
+ >>> from pyams_utils.list import random_iter
+ >>> mylist = [1, 2, 3, 2, 1]
+ >>> list(random_iter(mylist, 2))
+ [..., ...]
+ """
+ selected = [None] * limit
+ for index, item in enumerate(iterable):
+ if index < limit:
+ selected[index] = item
+ else:
+ selected_index = int(random() * (index+1))
+ if selected_index < limit:
+ selected[selected_index] = item
+ shuffle(selected)
+ return iter(selected)