def group_by(self, grouping_f):
"""
Group items by ``grouping_f``.
>>> foods = Linq([
... {'name': 'tomato', 'kind': 'Vegetable'},
... {'name': 'hormone', 'kind': 'Meat'},
... {'name': 'butdock root', 'kind': 'Vegetable'},
... {'name': 'pumpkin', 'kind': 'Vegetable'}
... ])
>>> foods.group_by(lambda f: f['kind'])
IGroup<
{Vegetable:
Linq<{'name': 'tomato', 'kind': 'Vegetable'},
{'name': 'butdock root', 'kind': 'Vegetable'},
{'name': 'pumpkin', 'kind': 'Vegetable'}>},
{Meat:
Linq<{'name': 'hormone', 'kind': 'Meat'}>}
>
"""
from ilinq.igroup import IPair, IGroup
group_dict = defaultdict(lambda: Linq([]))
for item in self[:]:
group_dict[grouping_f(item)].append(item)
return IGroup([IPair(*pair) for pair in group_dict.items()])
def test_str(self):
group = IGroup([IPair(0, Linq([0, 1, 2])), IPair(1, Linq([0, 1, 3]))])
assert_equal(str(group),
'IGroup<{0: Linq<0, 1, 2>}, {1: Linq<0, 1, 3>}>')
def test_values(self):
group = IGroup([IPair(0, Linq([0, 1, 2])), IPair(1, Linq([0, 1, 3]))])
assert_equal(group.values, [Linq([0, 1, 2]), Linq([0, 1, 3])])
def test_keys2(self):
group = IGroup([IPair(0, Linq([0, 1, 2])), IPair(1, Linq([0, 1, 3]))])
assert_equal(group.keys, [0, 1])
def test_init4(self):
IGroup([
IPair(0, Linq([1, 2, 3])),
IPair(1, Linq([2, 3, 4])),
IPair(1, Linq([2, 3, 4]))
])
def test_init3(self):
IGroup([0, IPair(1, Linq([1, 2, 3]))])
def test_init2(self):
IGroup([IPair(0, Linq([0, 1, 2]))])
def test_init(self):
assert_equal(IGroup().count(), 0)
def test_group_by(self):
linq = Linq(range(6))
assert_equal(
linq.group_by(lambda n: n % 2),
IGroup([IPair(0, Linq([0, 2, 4])),
IPair(1, Linq([1, 3, 5]))]))