Pythonic way of loading a list from a SQL table structure, python 3.x

Question

I imported a SQL table into a python list of lists and I would like to convert the format, in a kind of transpose manner, into a different format, where the key 'column' from the input table determines which elements are grouped in the output col. see example:

input list:

[
    (1, 'eq510240'),
    (1, 'eq510245'),
    (1, 'eq510246'),
    (2, 'eq510252'),
    (2, 'eq510291'),
    (3, 'eq510298')
]

desired output list:

[
    ('eq510240', 'eq510245', 'eq510246'),
    ('eq510252', 'eq510291'),
    ('eq510298')
]

Can you please show your attempt? Can you provide an minimal reproducible example of your attempt? Did you get an error? — Chris
– Chris, Commented Aug 31, 2017 at 13:28

Cory Kramer · Accepted Answer · 2017-08-31 13:30:49Z

3

You can use itertools.groupby to group the elements by the first value of each tuple. Then in a list comprehension create a tuple from the values in each group.

>>> from itertools import groupby
>>> [tuple(j[1] for j in g[1]) for g in groupby(l, key=lambda i: i[0])]
[('eq510240', 'eq510245', 'eq510246'),
 ('eq510252', 'eq510291'),
 ('eq510298',)]

answered Aug 31, 2017 at 13:30

Cory Kramer

119k19 gold badges176 silver badges233 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Pythonic way of loading a list from a SQL table structure, python 3.x

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest