Insert Incrament In Existing Array-CodePudding

I have an existing python3 tuple withdrawn from an sqlite3 table with dates "??-??-22" per row in accordance with the insertion date. I would like to insert another element in the python3 tuple that matches the date properly. In this case, an increment of a day number matching the date change. The number of rows per day are sometimes inconsistent. Hence, I am not inserting tuple back into database....Just using it for data visualization.

For example, [('06-08-22',otherData), ('06-08-22',), ('06-08-22',), ('06-08-22',), ('06-08-22',), ('06-09-22',), ('06-09-22',), ('06-09-22',), ...etc )]

------>>>

[('06-08-22',Day Number Here,), ('06-08-22',1,), ('06-08-22',1,), ('06-08-22',1,), ('06-08-22',1,), ('06-09-22',2,), ('06-09-22',2,), ('06-09-22',2,), ...etc )]

Solve by a for loop? Feels like overlooking something simple.

CodePudding user response：

You cannot insert new elements into a tuple, so you will have to convert each tuple to a list and then back to a tuple (or just leave them as lists if you don't really need them to stay tuples)

data = [
    ('06-08-22', 'A'),
    ('06-08-22', 'B'),
    ('06-09-22', 'C'),
    ('06-10-22', 'D'),
    ('06-10-22', 'E')
]


def transform_data(rows):
    day_num = 0
    last_date = None
    for row in rows:
        lst = list(row)
        if lst[0] != last_date:
            last_date = lst[0]
            day_num  = 1
        lst.insert(1, day_num)
        yield tuple(lst)


for row in transform_data(data):
    print(row)

Output:

('06-08-22', 1, 'A')
('06-08-22', 1, 'B')
('06-09-22', 2, 'C')
('06-10-22', 3, 'D')
('06-10-22', 3, 'E')

CodePudding user response：

If the records are sorted by day you could use groupby() and do

from itertools import groupby
from operator import itemgetter

records = [
    ('06-08-22', "A"),
    ('06-08-22',),
    ('06-08-22', "B"),
    ('06-08-22', "C"),
    ('06-08-22',),
    ('06-09-22', "D", "E"),
    ('06-09-22',),
    ('06-09-22', "F"),
    ('06-09-23',),
]

result = []
for n, (day, group) in enumerate(
        groupby(records, key=itemgetter(0)), start=1
    ):
    result.extend((day, n)   record[1:] for record in group)

which gives you the following result:

[('06-08-22', 1, 'A'),
 ('06-08-22', 1),
 ('06-08-22', 1, 'B'),
 ('06-08-22', 1, 'C'),
 ('06-08-22', 1),
 ('06-09-22', 2, 'D', 'E'),
 ('06-09-22', 2),
 ('06-09-22', 2, 'F'),
 ('06-09-23', 3)]