Peter Otten wrote:
> Functions to the rescue:
On second thought this was still more code than necessary.
Why not calculate a column on demand? Here's a self-containe example:
$ cat swanson_grouped_columns_virtual.py
import operator
from collections import defaultdict, namedtuple
def split_into_groups(records, key, GroupClass=list):
groups = defaultdict(GroupClass)
for record in records:
groups[key(record)].append(record)
return groups
class Group(list):
def __getattr__(self, name):
return [getattr(item, name) for item in self]
Record = namedtuple("Record", "title location")
records = [
Record("foo", "here"),
Record("foo", "there"),
Record("bar", "everywhere"),
]
groups = split_into_groups(
records,
operator.attrgetter("title"),
Group
)
print(groups["foo"].location)
$ python3 swanson_grouped_columns_virtual.py
['here', 'there']
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