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I'm having some issues trying to figure this out (as i'm a pure beginner to python).

I have a list of names: names_2 = ["Lars", "Per", "Henrik"]

Which I need to convert into a tuple who hold each elements length + the element it self.

I tried this:

namesTuple = tuple(names_2 + [len(name) for name in names_2])

Output of this is: ('Lars', 'Per', 'Henrik', 4, 3, 6)

The output im looking for is ('Lars', 4, 'Per', 3, 'Henrik', 6)

Anyone who can help?

Thor Christensen
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4 Answers4

3

You can use a nested generator expression in the tuple constructor, for instance:

names_tuple = tuple(x for name in names_2 for x in (name, len(name)))
# ('Lars', 4, 'Per', 3, 'Henrik', 6)

If you were to build it in a looping approach, it makes sense to build a list first (tuples are immutable):

names = []
for name in names_2:
    # extend (both at once)
    names.extend((name, len(name)))
    # OR append one by one (no spurious intermediate tuple)  
    # names.append(name)
    # names.append(len(name))
names_tuple = tuple(names)
user2390182
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  • Hmm... it's pretty much natural language. *"for every name in the names_2 list, make a pair of the name and its length, then make a tuple of all the elements from the resulting pairs"* – user2390182 Feb 02 '21 at 13:30
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names_2 = ["Lars", "Per", "Henrik"]
names = []
for name in names_2:
    names.append(name)
    names.append(len(name))
names = tuple(names)

Iterate over the names, append the name itself and its length to a list, and convert the list to tuple.
Or as a one-liner (but you'll end up with a tuple of tuples):

names_2 = ["Lars", "Per", "Henrik"]
names = tuple((name, len(name)) for name in names_2)
TheEagle
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0

Zip the list of names with the list of lengths, then flatten the resulting list and convert that to a tuple.

from itertools import chain

namesTuple = tuple(chain.from_iterable(zip(names_2, map(len, names_2))))

If you prefer something a little less "functional", you can use a generator expression.

namesTuple = tuple(chain.from_iterable((x, len(x)) for x in names_2))

or (repeating @schwobaseggl's answer)

namesTuple = tuple(value for name in names_2 for value in (name, len(name)))
chepner
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0

First create a tuple of tuples : ((name_1,lenght_1), (name_2,lenght_2),...) The zip function is existing for that.

Secondly, you have to flatten this tuple of tuples.

[In]
names = ["Lars", "Per", "Henrik"]

[In]
zip_tupled = tuple(zip(names, [len(x) for x in names]))

[Out]
zip_tupled = (('Lars', 4), ('Per', 3), ('Henrik', 6))

[In]
final = tuple(item for subtuple in zip_tupled for item in subtuple)

[Out]
final = ('Lars', 4, 'Per', 3, 'Henrik', 6)

This solution is quite close to the solution of schwobaseggl...But less direct/straight.

Stackoverflow : how to flatten a list

floupinette
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