Added compact()

CHANGELOG

@@ -1,3 +1,6 @@
+0.3.3
+- added compact()
+
 0.3.2
 - added ilen()
 - added some object helpers: namespace base class and @cached_property

README.rst

@@ -43,6 +43,7 @@ Select a part of collection::
     select(even, {1,2,3,10,20})                  # {2,10,20}
     select(re_tester('^a'), ('a','b','ab','ba')) # ('a','ab')
     select_keys(callable, {str: '', None: None}) # {str: ''}
+    compact({2, None, '', 0})                    # {2,'',0}
 
 
 Test collection contents::

docs/colls.rst

@@ -101,6 +101,15 @@ Transform and select
         select_values(bool, some_dict)
 
 
+.. function:: compact(pred, coll)
+
+    Removes ``None`` values from given collection. When compacting a dict all keys with ``None`` values are trashed.
+
+    Extract integer data from request::
+
+        compact(walk_values(silent(int), request_dict))
+
+
 Dict utils
 ----------
 

from_underscore.txt

@@ -3,7 +3,7 @@ countby
 foldl?=reduce foldr?
 
 # Array
-compact=keep/1? without(relates to conj)
+without(relates to conj)
 flatten?
 
 # Functions

funcy/colls.py

@@ -8,7 +8,7 @@
 
 
 __all__ = ['empty', 'iteritems', 'join', 'merge',
-           'walk', 'walk_keys', 'walk_values', 'select', 'select_keys', 'select_values',
+           'walk', 'walk_keys', 'walk_values', 'select', 'select_keys', 'select_values', 'compact',
            'is_distinct', 'all', 'any', 'none', 'one', 'some',
            'zipdict', 'flip', 'project',
            'where', 'pluck', 'invoke']
@@ -90,6 +90,15 @@ def select_keys(pred, coll):
 def select_values(pred, coll):
     return select(lambda (k, v): pred(v), coll)
 
+
+def compact(coll):
+    pred = lambda x: x is not None
+    if isinstance(coll, Mapping):
+        return select_values(pred, coll)
+    else:
+        return select(pred, coll)
+
+
 ### Content tests
 
 def is_distinct(coll):

tests/test_colls.py

@@ -88,6 +88,10 @@ def test_select_keys():
 def test_select_values():
     assert select_values(_ % 2, {'a': 1, 'b': 2}) == {'a': 1}
 
+def test_compact():
+    assert eq(compact([0, 1, None, 3]), [0, 1, 3])
+    assert eq(compact((0, 1, None, 3)), (0, 1, 3))
+    assert eq(compact({'a': None, 'b': 0, 'c': 1}), {'b': 0, 'c': 1})
 
 def test_is_distinct():
     assert is_distinct('abc')