[Tutor] Flatten a list in tuples and remove doubles

[Prasad, Ramit]

> I would get a new list as:
> 
> [(0, '3eA', 'Dupont', 'Juliette', '11.0/10.0', '4.0/5.0', '17.5/30.0',
> '3.0/5.0', '4.5/10.0', '35.5/60.0'), (1, '3eA', 'Pop', 'Iggy',
> '12.0/10.0', '3.5/5.0', '11.5/30.0', '4.0/5.0', '5.5/10.0',
> '7.5/10.0', '40.5/60.0')]
> 
> ... from this one:
> 
> [(0, '3eA', 'Dupont', 'Juliette', 0, 11.0, 10.0), (0, '3eA', 'Dupont',
> 'Juliette', 1, 4.0, 5.0), (0, '3eA', 'Dupont', 'Juliette', 2, 17.5,
> 30.0), (0, '3eA', 'Dupont', 'Juliette', 3, 3.0, 5.0), (0, '3eA',
> 'Dupont', 'Juliette', 4, 4.5, 10.0), (0, '3eA', 'Dupont', 'Juliette',
> 5, 35.5, 60.0), (1, '3eA', 'Pop', 'Iggy', 0, 12.0, 10.0), (1, '3eA',
> 'Pop', 'Iggy', 1, 3.5, 5.0), (1, '3eA', 'Pop', 'Iggy', 2, 11.5, 30.0),
> (1, '3eA', 'Pop', 'Iggy', 3, 4.0, 5.0), (1, '3eA', 'Pop', 'Iggy', 4,
> 5.5, 10.0), (1, '3eA', 'Pop', 'Iggy', 5, 40.5, 60.0)]
> 
> How to make that ? I'm looking for but for now I can't do it.


Well first thing to do would be to describe the logic behind what
you are doing. Without knowing that it is difficult to come up
with the correct solution. I am guessing you want a list
where fields 1,2,3 (based on the first element being field 0) 
of field a string of `field 5 + '/' + field 6`. But that does
not tell me what field 0 should be in the new format.

This is a pretty crude sample that should work for you.

lookup = {}

for row in old_list:
    key = (row[1],row[2],row[3])
    field_0, ratios = lookup.setdefault( key, (row[0], []) )
    ratios.append( '{0}/{1}'.format( row[5], row[6] ) )
new_list = []
for key, value in lookup.items():
    row = [ value[0], key[0], key[1], key[2] ]
    row.extend(value[1])
    new_list.append(tuple(row))

# Might need to sort to get the exact same results


Ramit

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