Aggregate with key is none

docs/changes.rst

@@ -4,6 +4,9 @@ Changes
 Version 1.7.2
 -------------
 
+* Allow aggregation over the entire table (without a key)
+  By :user:`bmaggard`.
+
 * Allow specifying output field name for simple aggregation
   By :user:`bmaggard`, :issue:`370`.
 

petl/test/transform/test_reductions.py

@@ -133,7 +133,46 @@ def test_aggregate_simple():
                ('c', 1))
     ieq(expect5, table5)
     ieq(expect5, table5)
-
+
+
+def test_aggregate_simple_key_is_None():
+
+    table1 = (('foo', 'bar', 'baz'),
+              ('a', 3, True),
+              ('a', 7, False),
+              ('b', 2, True),
+              ('b', 2, False),
+              ('b', 9, False),
+              ('c', 4, True))
+
+    # simplest signature - aggregate whole rows
+    table2 = aggregate(table1, None, len)
+    expect2 = (('value',), (6,))
+    ieq(expect2, table2)
+    ieq(expect2, table2)
+
+    # next simplest signature - aggregate single field
+    table3 = aggregate(table1, None, sum, 'bar')
+    expect3 = (('value',), (27,))
+    ieq(expect3, table3)
+    ieq(expect3, table3)
+
+    # alternative signature for simple aggregation
+    table4 = aggregate(table1, key=None, aggregation=list,
+                       value=('bar', 'baz'))
+    expect4 = (('value',),
+               ( [(3, True), (7, False),
+                 (2, True), (2, False), (9, False),
+                 (4, True)],),)
+
+    ieq(expect4, table4)
+    ieq(expect4, table4)
+
+    table5 = aggregate(table1, None, len, field='nrows')
+    expect5 = (('nrows',), (6,))
+    ieq(expect5, table5)
+    ieq(expect5, table5)
+
 def test_aggregate_multifield():
 
     table1 = (('foo', 'bar'),
@@ -186,10 +225,57 @@ def test_aggregate_multifield():
     table4 = aggregate(table1, 'foo', aggregators)
     ieq(expect2, table4)
     ieq(expect2, table4)  # check can iterate twice
-
-
+
+def test_aggregate_multifield_key_is_None():
+
+    table1 = (('foo', 'bar'),
+              ('a', 3),
+              ('a', 7),
+              ('b', 2),
+              ('b', 1),
+              ('b', 9),
+              ('c', 4))
+
+    # dict arg
+    aggregators = OrderedDict()
+    aggregators['count'] = len
+    aggregators['minbar'] = 'bar', min
+    aggregators['maxbar'] = 'bar', max
+    aggregators['sumbar'] = 'bar', sum
+    aggregators['listbar'] = 'bar', list
+    aggregators['bars'] = 'bar', strjoin(', ')
+
+    table2 = aggregate(table1, None, aggregators)
+    expect2 = (('count', 'minbar', 'maxbar', 'sumbar', 'listbar',
+                'bars'),
+               (6, 1, 9, 26, [3, 7, 2, 1, 9, 4], '3, 7, 2, 1, 9, 4'))
+    ieq(expect2, table2)
+    ieq(expect2, table2)  # check can iterate twice
+
+    # use suffix notation
+    table3 = aggregate(table1, None)
+    table3['count'] = len
+    table3['minbar'] = 'bar', min
+    table3['maxbar'] = 'bar', max
+    table3['sumbar'] = 'bar', sum
+    table3['listbar'] = 'bar'  # default aggregation is list
+    table3['bars'] = 'bar', strjoin(', ')
+    ieq(expect2, table3)
+
+    # list arg
+    aggregators = [('count', len),
+                   ('minbar', 'bar', min),
+                   ('maxbar', 'bar', max),
+                   ('sumbar', 'bar', sum),
+                   ('listbar', 'bar', list),
+                   ('bars', 'bar', strjoin(', '))]
+
+    table4 = aggregate(table1, None, aggregators)
+    ieq(expect2, table4)
+    ieq(expect2, table4)  # check can iterate twice
+
 def test_aggregate_more():
-    
+
     table1 = (('foo', 'bar'),
               ('aa', 3),
               ('aa', 7),
@@ -198,7 +284,7 @@ def test_aggregate_more():
               ('bb', 9),
               ('cc', 4),
               ('dd', 3))
-    
+
     aggregators = OrderedDict()
     aggregators['minbar'] = 'bar', min
     aggregators['maxbar'] = 'bar', max
@@ -214,18 +300,51 @@ def test_aggregate_more():
                ('dd', 3, 3, 3, [3], '3'))
     ieq(expect2, table2)
     ieq(expect2, table2)  # check can iterate twice
-    
+
     table3 = aggregate(table1, 'foo')
     table3['minbar'] = 'bar', min
     table3['maxbar'] = 'bar', max
     table3['sumbar'] = 'bar', sum
     table3['listbar'] = 'bar'  # default aggregation is list
     table3['bars'] = 'bar', strjoin(', ')
     ieq(expect2, table3)
-
-
+
+def test_aggregate_more_key_is_None():
+
+    table1 = (('foo', 'bar'),
+              ('aa', 3),
+              ('aa', 7),
+              ('bb', 2),
+              ('bb', 1),
+              ('bb', 9),
+              ('cc', 4),
+              ('dd', 3))
+
+    aggregators = OrderedDict()
+    aggregators['minbar'] = 'bar', min
+    aggregators['maxbar'] = 'bar', max
+    aggregators['sumbar'] = 'bar', sum
+    aggregators['listbar'] = 'bar'  # default aggregation is list
+    aggregators['bars'] = 'bar', strjoin(', ')
+
+    table2 = aggregate(table1, None, aggregators)
+    expect2 = (('minbar', 'maxbar', 'sumbar', 'listbar', 'bars'),
+               (1, 9, 29,
+                   [3, 7, 2, 1, 9, 4, 3],
+                   '3, 7, 2, 1, 9, 4, 3'))
+    ieq(expect2, table2)
+    ieq(expect2, table2)  # check can iterate twice
+
+    table3 = aggregate(table1, None)
+    table3['minbar'] = 'bar', min
+    table3['maxbar'] = 'bar', max
+    table3['sumbar'] = 'bar', sum
+    table3['listbar'] = 'bar'  # default aggregation is list
+    table3['bars'] = 'bar', strjoin(', ')
+    ieq(expect2, table3)
+
 def test_aggregate_multiple_source_fields():
-    
+
     table = (('foo', 'bar', 'baz'),
              ('a', 3, True),
              ('a', 7, False),
@@ -255,11 +374,40 @@ def test_aggregate_multiple_source_fields():
     ieq(expect, actual)
     ieq(expect, actual)    
 
-
+def test_aggregate_multiple_source_fields_key_is_None():
+
+    table = (('foo', 'bar', 'baz'),
+             ('a', 3, True),
+             ('a', 7, False),
+             ('b', 2, True),
+             ('b', 2, False),
+             ('b', 9, False),
+             ('c', 4, True))
+
+    expect  = (('value',),
+               ( [(3, True), (7, False),
+                 (2, True), (2, False), (9, False),
+                 (4, True)],),)
+
+    actual = aggregate(table, None, list, ('bar', 'baz'))
+    ieq(expect, actual)
+    ieq(expect, actual)
+
+    actual = aggregate(table, key=None, aggregation=list,
+                       value=('bar', 'baz'))
+    ieq(expect, actual)
+    ieq(expect, actual)
+
+    actual = aggregate(table, key=None)
+    actual['value'] = ('bar', 'baz'), list
+    ieq(expect, actual)
+    ieq(expect, actual)
+
+
 def test_aggregate_empty():
-    
+
     table = (('foo', 'bar'),)
-    
+
     aggregators = OrderedDict()
     aggregators['minbar'] = 'bar', min
     aggregators['maxbar'] = 'bar', max
@@ -269,6 +417,18 @@ def test_aggregate_empty():
     expect = (('foo', 'minbar', 'maxbar', 'sumbar'),)
     ieq(expect, actual)
 
+def test_aggregate_empty_key_is_None():
+
+    table = (('foo', 'bar'),)
+
+    aggregators = OrderedDict()
+    aggregators['minbar'] = 'bar', min
+    aggregators['maxbar'] = 'bar', max
+    aggregators['sumbar'] = 'bar', sum
+
+    actual = aggregate(table, None, aggregators)
+    expect = (('minbar', 'maxbar', 'sumbar'),)
+    ieq(expect, actual)
 
 def test_mergeduplicates():