Printing and formatting a tuple in python

Question

I have this:

record = (u'U9', [(u'U2', 1.0), (u'U10', 0.6666666666666666), (u'U2', 1.0)])

I want this as an printed output to a file:

U9:U2,U10

Note: Only unique values are needed in the output ( U2 is printed only once despite appearing twice)

I have tried using:

for i in record[1]:
   print record[1], ":", record[i[0]]

But this gives me:

U9:U2
U9:U10
U9:U2

Answer 1

Extract the unique values into a set, then join those into a single string:

unique = {t[0] for t in record[1]}
print '{}:{}'.format(record[0], ','.join(unique))

Demo:

>>> record = (u'U9', [(u'U2', 1.0), (u'U10', 0.6666666666666666), (u'U2', 1.0)])
>>> unique = {t[0] for t in record[1]}
>>> print '{}:{}'.format(record[0], ','.join(unique))
U9:U10,U2

Note that sets are unordered, which is why you get U10,U2 for this input, and not U2,U10 . See Why is the order in dictionaries and sets arbitrary?

If order matters, convert your list of key-value pairs to an collections.OrderedDict() object , and get the keys from the result:

>>> from collections import OrderedDict
>>> unique = OrderedDict(record[1])
>>> print '{}:{}'.format(record[0], ','.join(unique))
U9:U2,U10