grouping and sorting within groups using another list
I have a list of tuples, and I want to group them by 3 items (0, 3, 4)
and then within each group sort the data by a 4th item (6) using a
sort order from another list. The list is always ordered by the 3
grouping items.
For example, if I have this list:
rows =
[('a', 'b', 'c', 'd', 'e', 'f', 'blue', ),
('a', 'x', 'y', 'd', 'e', 'f', 'green', ),
('a', 'q', 'w', 'd', 'e', 'f', 'white', ),
('p', 'x', 'y', 'd', 'e', 'f', 'white', ),
('p', 'x', 'y', 'd', 'e', 'f', ' 'blue', ...),
('p', 'x', 'y', 'd', 'e', 'f', ' 'green', ...),
('z', 'x', 'y', 'm', 'n', 'o', 'green, ...),
('z', 'x', 'y', 'm', 'n', 'o', 'white, ...),
('z', 'x', 'y', 'm', 'n', 'o', 'blue, ...),
]
and I have a list:
sort_list = ['blue', 'white', 'green']
Then the result list would be:
[('a', 'b', 'c', 'd', 'e', 'f', 'blue', ),
('a', 'x', 'y', 'd', 'e', 'f', 'white', ),
('a', 'q', 'w', 'd', 'e', 'f', 'green', ),
('p', 'x', 'y', 'd', 'e', 'f', 'blue', ),
('p', 'x', 'y', 'd', 'e', 'f', ' 'white', ...),
('p', 'x', 'y', 'd', 'e', 'f', ' 'green', ...),
('z', 'x', 'y', 'm', 'n', 'o', 'blue, ...),
('z', 'x', 'y', 'm', 'n', 'o', 'white, ...),
('z', 'x', 'y', 'm', 'n', 'o', 'green, ...),
]
Been trying to do with using groupby but have not been successful.
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RE: grouping and sorting within groups using another list
Would it be something as simple as:
rows.sort(key = lambda x: (x[0], x[3], x[4], sort_list.index(x[6])))
-Original Message-
From: Python-list On
Behalf Of Larry Martell
Sent: Wednesday, September 2, 2020 1:55 PM
To: Python
Subject: grouping and sorting within groups using another list
I have a list of tuples, and I want to group them by 3 items (0, 3, 4)
and then within each group sort the data by a 4th item (6) using a
sort order from another list. The list is always ordered by the 3
grouping items.
For example, if I have this list:
rows =
[('a', 'b', 'c', 'd', 'e', 'f', 'blue', ),
('a', 'x', 'y', 'd', 'e', 'f', 'green', ),
('a', 'q', 'w', 'd', 'e', 'f', 'white', ),
('p', 'x', 'y', 'd', 'e', 'f', 'white', ),
('p', 'x', 'y', 'd', 'e', 'f', ' 'blue', ...),
('p', 'x', 'y', 'd', 'e', 'f', ' 'green', ...),
('z', 'x', 'y', 'm', 'n', 'o', 'green, ...),
('z', 'x', 'y', 'm', 'n', 'o', 'white, ...),
('z', 'x', 'y', 'm', 'n', 'o', 'blue, ...),
]
and I have a list:
sort_list = ['blue', 'white', 'green']
Then the result list would be:
[('a', 'b', 'c', 'd', 'e', 'f', 'blue', ),
('a', 'x', 'y', 'd', 'e', 'f', 'white', ),
('a', 'q', 'w', 'd', 'e', 'f', 'green', ),
('p', 'x', 'y', 'd', 'e', 'f', 'blue', ),
('p', 'x', 'y', 'd', 'e', 'f', ' 'white', ...),
('p', 'x', 'y', 'd', 'e', 'f', ' 'green', ...),
('z', 'x', 'y', 'm', 'n', 'o', 'blue, ...),
('z', 'x', 'y', 'm', 'n', 'o', 'white, ...),
('z', 'x', 'y', 'm', 'n', 'o', 'green, ...),
]
Been trying to do with using groupby but have not been successful.
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Re: grouping and sorting within groups using another list
Larry Martell wrote:
> I have a list of tuples, and I want to group them by 3 items (0, 3, 4)
> and then within each group sort the data by a 4th item (6) using a
> sort order from another list. The list is always ordered by the 3
> grouping items.
>From your description I deduced
from itertools import chain, groupby
from operator import itemgetter
from pprint import pprint
rows = [
('a', 'b', 'c', 'd', 'e', 'f', 'blue', ...),
('a', 'x', 'y', 'd', 'e', 'f', 'green', ...),
('a', 'q', 'w', 'd', 'e', 'f', 'white', ...),
('p', 'x', 'y', 'd', 'e', 'f', 'white', ...),
('p', 'x', 'y', 'd', 'e', 'f', 'blue', ...),
('p', 'x', 'y', 'd', 'e', 'f', 'green', ...),
('z', 'x', 'y', 'm', 'n', 'o', 'green', ...),
('z', 'x', 'y', 'm', 'n', 'o', 'white', ...),
('z', 'x', 'y', 'm', 'n', 'o', 'blue', ...),
]
sort_list = ['blue', 'white', 'green']
wanted = [
('a', 'b', 'c', 'd', 'e', 'f', 'blue', ...),
('a', 'x', 'y', 'd', 'e', 'f', 'white', ...),
('a', 'q', 'w', 'd', 'e', 'f', 'green', ...),
('p', 'x', 'y', 'd', 'e', 'f', 'blue', ...),
('p', 'x', 'y', 'd', 'e', 'f', 'white', ...),
('p', 'x', 'y', 'd', 'e', 'f', 'green', ...),
('z', 'x', 'y', 'm', 'n', 'o', 'blue', ...),
('z', 'x', 'y', 'm', 'n', 'o', 'white', ...),
('z', 'x', 'y', 'm', 'n', 'o', 'green', ...),
]
group_key = itemgetter(0, 3, 4)
def sort_key(row, lookup={k: i for i, k in enumerate(sort_list)}):
return lookup[row[6]]
result = list(
chain.from_iterable(
sorted(group, key=sort_key)
for _key, group in groupby(rows, key=group_key)
)
)
pprint(wanted)
pprint(result)
assert result == wanted
Unfortunately the assertion fails. I'm not sure whether I misunderstood your
description or if your sample data is incorrect.
>
> For example, if I have this list:
> rows =
> [('a', 'b', 'c', 'd', 'e', 'f', 'blue', ),
> ('a', 'x', 'y', 'd', 'e', 'f', 'green', ),
> ('a', 'q', 'w', 'd', 'e', 'f', 'white', ),
> ('p', 'x', 'y', 'd', 'e', 'f', 'white', ),
> ('p', 'x', 'y', 'd', 'e', 'f', ' 'blue', ...),
> ('p', 'x', 'y', 'd', 'e', 'f', ' 'green', ...),
> ('z', 'x', 'y', 'm', 'n', 'o', 'green, ...),
> ('z', 'x', 'y', 'm', 'n', 'o', 'white, ...),
> ('z', 'x', 'y', 'm', 'n', 'o', 'blue, ...),
> ]
>
> and I have a list:
>
> sort_list = ['blue', 'white', 'green']
>
> Then the result list would be:
>
> [('a', 'b', 'c', 'd', 'e', 'f', 'blue', ),
> ('a', 'x', 'y', 'd', 'e', 'f', 'white', ),
> ('a', 'q', 'w', 'd', 'e', 'f', 'green', ),
> ('p', 'x', 'y', 'd', 'e', 'f', 'blue', ),
> ('p', 'x', 'y', 'd', 'e', 'f', ' 'white', ...),
> ('p', 'x', 'y', 'd', 'e', 'f', ' 'green', ...),
> ('z', 'x', 'y', 'm', 'n', 'o', 'blue, ...),
> ('z', 'x', 'y', 'm', 'n', 'o', 'white, ...),
> ('z', 'x', 'y', 'm', 'n', 'o', 'green, ...),
> ]
>
> Been trying to do with using groupby but have not been successful.
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Re: grouping and sorting within groups using another list
Peter Otten wrote:
> group_key = itemgetter(0, 3, 4)
>
>
> def sort_key(row, lookup={k: i for i, k in enumerate(sort_list)}):
> return lookup[row[6]]
>
>
> result = list(
> chain.from_iterable(
> sorted(group, key=sort_key)
> for _key, group in groupby(rows, key=group_key)
> )
> )
It just occured to me that if the above code is what you want you can omit
the groupby and sort with a combined key:
sorted(rows, key=lambda row: (group_key(row), sort_key(row)))
(The lambda is for illustration, you could of course merge the two key
functions into one)
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Re: grouping and sorting within groups using another list
On Wed, Sep 2, 2020 at 11:22 AM David Raymond wrote:
>
> Would it be something as simple as:
>
> rows.sort(key = lambda x: (x[0], x[3], x[4], sort_list.index(x[6])))
This is perfect - thanks!
> -Original Message-
> From: Python-list
> On Behalf Of Larry Martell
> Sent: Wednesday, September 2, 2020 1:55 PM
> To: Python
> Subject: grouping and sorting within groups using another list
>
> I have a list of tuples, and I want to group them by 3 items (0, 3, 4)
> and then within each group sort the data by a 4th item (6) using a
> sort order from another list. The list is always ordered by the 3
> grouping items.
>
> For example, if I have this list:
> rows =
> [('a', 'b', 'c', 'd', 'e', 'f', 'blue', ),
> ('a', 'x', 'y', 'd', 'e', 'f', 'green', ),
> ('a', 'q', 'w', 'd', 'e', 'f', 'white', ),
> ('p', 'x', 'y', 'd', 'e', 'f', 'white', ),
> ('p', 'x', 'y', 'd', 'e', 'f', ' 'blue', ...),
> ('p', 'x', 'y', 'd', 'e', 'f', ' 'green', ...),
> ('z', 'x', 'y', 'm', 'n', 'o', 'green, ...),
> ('z', 'x', 'y', 'm', 'n', 'o', 'white, ...),
> ('z', 'x', 'y', 'm', 'n', 'o', 'blue, ...),
> ]
>
> and I have a list:
>
> sort_list = ['blue', 'white', 'green']
>
> Then the result list would be:
>
> [('a', 'b', 'c', 'd', 'e', 'f', 'blue', ),
> ('a', 'x', 'y', 'd', 'e', 'f', 'white', ),
> ('a', 'q', 'w', 'd', 'e', 'f', 'green', ),
> ('p', 'x', 'y', 'd', 'e', 'f', 'blue', ),
> ('p', 'x', 'y', 'd', 'e', 'f', ' 'white', ...),
> ('p', 'x', 'y', 'd', 'e', 'f', ' 'green', ...),
> ('z', 'x', 'y', 'm', 'n', 'o', 'blue, ...),
> ('z', 'x', 'y', 'm', 'n', 'o', 'white, ...),
> ('z', 'x', 'y', 'm', 'n', 'o', 'green, ...),
> ]
>
> Been trying to do with using groupby but have not been successful.
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