CODEWITHSUNDEEP
pythonpython-2.7listtupleslist-comprehension
Gerry Julian
Gerry Julian

Reputation: 43

New tuple from a mess tuple

I'm facing a trouble with creating a new tuple. I'm kinda new in python.

Suppose I have a list of tuple :

a = [1,2,6,4,5]
b = [3,7,3,4,6]
[((11, 5, 6), n), ((9, 6, 3), n), ((9, 2, 7), n), ((8, 4, 4), n), ((4, 1, 3), n)]

which belongs to [(a+b,a,b),n=count(zip(a,b)),...........]

My final goal is to make a tuple like this: (removing a+b, and put 'n' value into the tuple)

[(5,6,n), (6,3,n), .... ] 
[(a,b,n),  .....]

is there a way to make this happen?

Upvotes: 0

Views: 97

Answers (3)

Nikaido
Nikaido

Reputation: 4629

I don't understand very well your question, but suppose we know the 'n' value for every tuple (i fixed my n's to 1)

The naive solution is (without tuple unpacking)

n = 1
x = [((11, 5, 6), n), ((9, 6, 3), n), ((9, 2, 7), n), ((8, 4, 4), n), ((4, 1, 3), n)]
y= [(tuple_[0][1],tuple_[0][2], tuple_[1]) for tuple_ in x]
print(y)

which prints

[(5, 6, 1), (6, 3, 1), (2, 7, 1), (4, 4, 1), (1, 3, 1)]

Upvotes: 0

Dan D.
Dan D.

Reputation: 74675

Simply use tuple unpacking:

[(a, b, n) for ((_, a, b), n) in T]

Where T is the input and the result is in the requested form.

Example:

>>> T = [((11, 5, 6), 1), ((9, 6, 3), 2), ((9, 2, 7), 3), ((8, 4, 4), 4), ((4, 1, 3), 5)]
>>> [(a, b, n) for ((_, a, b), n) in T]
[(5, 6, 1), (6, 3, 2), (2, 7, 3), (4, 4, 4), (1, 3, 5)]

I've replaced the n's with numbers 1 to 5.

Upvotes: 1

user305883
user305883

Reputation: 1741

It is a bit confusing what you wrote.

Maybe you want this:

zip(a,b,[sum(x) for x in zip(a,b)])

What it does:

  1. zip() returs a list of tuples

Note that tuples and list are two different data structures. In your question, a = [] and b = [] are lists of integers, not tuples.

  1. a syntax of [ f(x) for x in g(y,z)] is equivalent to pseudo-code:

    for each_item in iterable_like_a_list_is:
     apply f() to each_item
     return a list of f(x) items

It is a list comprehension.

  1. finally apply zip(x, y, z) to three lists. In your case, a, b and the a+b obtained at step 2.

Upvotes: 0

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