-

cool-RR · cool-RR · commit a77519fa87b0 · 2015-06-26T20:58:46.000+03:00
diff --git a/source_py3/python_toolbox/sequence_tools/misc.py b/source_py3/python_toolbox/sequence_tools/misc.py
@@ -57,20 +57,24 @@ def partitions(sequence, partition_size=None, *, n_partitions=None,
                allow_remainder=True, larger_on_remainder=False,
                fill_value=NO_FILL_VALUE):
     '''
-    Partition `sequence` into equal partitions of size `partition_size`, or
+    Break `sequence` into partitions.
+    
+    Partitions `sequence` into partitions of size `partition_size`, or
     determine size automatically given the number of partitions as
     `n_partitions`.
 
-    If the sequence can't be divided into precisely equal partitions, the last
-    partition will contain less members than all the other partitions.
+    This function attempts to break the sequence into partitions with an equal
+    number of items; if the sequence can't be divided into precisely equal
+    partitions, the first partitions will have more elements then the
+    partitions that come after them.
 
     Example:
 
         >>> partitions([0, 1, 2, 3, 4], 2)
         [[0, 1], [2, 3], [4]]
 
-    (You need to give *either* a `partition_size` *or* an `n_partitions`
-    argument, not both.)
+    You need to give *either* a `partition_size` *or* an `n_partitions`
+    argument, not both.
 
     Specify `allow_remainder=False` to enforce that the all the partition sizes
     be equal; if there's a remainder while `allow_remainder=False`, an
@@ -101,6 +105,8 @@ def partitions(sequence, partition_size=None, *, n_partitions=None,
     sequence = ensure_iterable_is_sequence(sequence)
 
     sequence_length = len(sequence)
+    if 0 in (n_partitions, partition_size):
+        raise ValueError
 
     ### Validating input: #####################################################
     #                                                                         #
diff --git a/source_py3/test_python_toolbox/test_sequence_tools/test_partitions.py b/source_py3/test_python_toolbox/test_sequence_tools/test_partitions.py
@@ -117,4 +117,34 @@ def test_different_types():
         assert partitions(sequence, partition_size=2,
                           larger_on_remainder=True) == [
             sequence[:2], sequence[2:]
-        ]
+        ]
+        
+def test_n_partitions():
+    r = list(range(10))
+    with cute_testing.RaiseAssertor(ValueError):
+        partitions(r, n_partitions=0)
+    assert partitions(r, n_partitions=1) == [[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]]
+    assert partitions(r, n_partitions=2) == [[0, 1, 2, 3, 4], [5, 6, 7, 8, 9]]
+    assert partitions(r, n_partitions=3) == \
+                                           [[0, 1, 2, 3], [4, 5, 6,], [7, 8, 9]]
+    assert partitions(r, n_partitions=4) == \
+                                        [[0, 1, 2], [3, 4, 5], [6, 7], [8, 9]]
+    assert partitions(r, n_partitions=5) == \
+                                       [[0, 1], [2, 3], [4, 5], [6, 7], [8, 9]]
+    assert partitions(r, n_partitions=6) == \
+                                     [[0, 1], [2, 3], [4, 5], [6, 7], [8], [9]]
+    assert partitions(r, n_partitions=7) == \
+                                   [[0, 1], [2, 3], [4, 5], [6], [7], [8], [9]]
+    assert partitions(r, n_partitions=8) == \
+                                 [[0, 1], [2, 3], [4], [5], [6], [7], [8], [9]]
+    assert partitions(r, n_partitions=9) == \
+                               [[0, 1], [2], [3], [4], [5], [6], [7], [8], [9]]
+    assert partitions(r, n_partitions=10) == \
+                             [[0], [1], [2], [3], [4], [5], [6], [7], [8], [9]]
+    assert partitions(r, n_partitions=11) == \
+                         [[0], [1], [2], [3], [4], [5], [6], [7], [8], [9], []]
+    assert partitions(r, n_partitions=12) == \
+                     [[0], [1], [2], [3], [4], [5], [6], [7], [8], [9], [], []]
+           
+    # blocktodo: add same batch of tests but with larger_on_remainder
+    
