more set/list stuff

docs/docsite/rst/playbooks_filters.rst

@@ -609,6 +609,41 @@ To get date object from string use the `to_datetime` filter, (new in version in
     # get amount of seconds between two dates, default date format is %Y-%d-%m %H:%M:%S but you can pass your own one
     {{ (("2016-08-04 20:00:12"|to_datetime) - ("2015-10-06"|to_datetime('%Y-%d-%m'))).seconds  }}
 
+
+Combination Filters
+````````````````````
+
+.. versionadded:: 2.3
+
+This set of filters returns a list of combined lists.
+To get permutations of a list::
+
+    - name: give me largest permutations (order matters)
+      debug: msg="{{ [1,2,3,4,5]|permutations|list }}"
+
+    - name: give me permutations of sets of 3
+      debug: msg="{{ [1,2,3,4,5]|permutations(3)|list }}"
+
+Combinations always require a set size::
+
+    - name: give me combinations for sets of 2
+      debug: msg="{{ [1,2,3,4,5]|combinations(2)|list }}"
+
+
+To get a list combining the elements of other lists use ``zip``::
+
+    - name: give me list combo of 2 lists 
+      debug: msg="{{ [1,2,3,4,5]|zip(['a','b','c','d','e','f'])|list }}"
+
+    - name: give me shortest combo of 2 lists
+      debug: msg="{{ [1,2,3]|zip(['a','b','c','d','e','f'])|list }}"
+
+To always exhaust all list use ``zip_longest``::
+
+    - name: give me longest combo of 3 lists , fill with X
+      debug: msg="{{ [1,2,3]|zip_longest(['a','b','c','d','e','f'], [21, 22, 23], fillvalue='X')|list }}"
+
+
 Debugging Filters
 `````````````````
 

lib/ansible/plugins/filter/mathstuff.py

@@ -22,9 +22,12 @@ __metaclass__ = type
 
 import math
 import collections
+import itertools
+
 from ansible import errors
 from ansible.module_utils import basic
 
+
 def unique(a):
     if isinstance(a,collections.Hashable):
         c = set(a)
@@ -117,7 +120,7 @@ class FilterModule(object):
     ''' Ansible math jinja2 filters '''
 
     def filters(self):
-        return {
+        filters = {
             # general math
             'min' : min,
             'max' : max,
@@ -134,8 +137,25 @@ class FilterModule(object):
             'symmetric_difference': symmetric_difference,
             'union': union,
 
+            # combinatorial
+            'permutations': itertools.permutations,
+            'combinations': itertools.combinations,
+
             # computer theory
             'human_readable' : human_readable,
             'human_to_bytes' : human_to_bytes,
 
         }
+
+        # py2 vs py3, reverse when py3 is predominant version
+        try:
+            filters['zip'] = itertools.izip
+            filters['zip_longest'] = itertools.izip_longest
+        except AttributeError:
+            try:
+                filters['zip'] = itertools.zip
+                filters['zip_longest'] = itertools.zip_longest
+            except:
+                pass
+
+        return filters