a question about zip...

[KraftDiner]

I had a structure that looked like this
((0,1), (2, 3), (4, 5), (6,7)

I changed my code slightly and now I do this:
odd = (1,3,5,7)
even = (0,2,4,6)
all = zip(even, odd)

however the zip produces:
[(0, 1), (2, 3), (4, 5), (6, 7)]

Which is a list of tuples.. I wanted a tuple of tuples...

 

[Jan Niklas Fingerle]

[(0, 1), (2, 3), (4, 5), (6, 7)]

Which is a list of tuples.. I wanted a tuple of tuples...

odd = (1,3,5,7)
even = (0,2,4,6)
all = zip(even, odd)
all [(0, 1), (2, 3), (4, 5), (6, 7)]
tuple(all)

((0, 1), (2, 3), (4, 5), (6, 7))

Cheers,
--Jan Niklas

 

[Diez B. Roggisch]

I had a structure that looked like this
((0,1), (2, 3), (4, 5), (6,7)

I changed my code slightly and now I do this:
odd = (1,3,5,7)
even = (0,2,4,6)
all = zip(even, odd)

however the zip produces:
[(0, 1), (2, 3), (4, 5), (6, 7)]

Which is a list of tuples.. I wanted a tuple of tuples...

Use tuple(zip(...))

There is a reason that zip returns a list: appending to a list is considered a "natural" operation, whereas extending an
immutable(!) tuple creates a _new_ tuple for each entry. Which is a comparable costly operation - actually quadratic
complexity instead of linear.

So - if you need a tuple afterwards, convert it as shown above.

Diez

 

[Xavier Morel]

I had a structure that looked like this
((0,1), (2, 3), (4, 5), (6,7)

I changed my code slightly and now I do this:
odd = (1,3,5,7)
even = (0,2,4,6)
all = zip(even, odd)

however the zip produces:
[(0, 1), (2, 3), (4, 5), (6, 7)]

Which is a list of tuples.. I wanted a tuple of tuples...

tuple(zip(even, odd))

and if you fear for memory efficiency

tuple(iterator.izip(even, odd))

 

[Steven D'Aprano]

I had a structure that looked like this
((0,1), (2, 3), (4, 5), (6,7)

I changed my code slightly and now I do this:
odd = (1,3,5,7)
even = (0,2,4,6)
all = zip(even, odd)

however the zip produces:
[(0, 1), (2, 3), (4, 5), (6, 7)]

Which is a list of tuples.. I wanted a tuple of tuples...

Others have already told you how to do this. But I have
a question: why do you care that it is a tuple, not a
list? Is there something you need to do with it that
can be done with tuples but not lists?

In other words, while it isn't *wrong* to convert the
list to a tuple, perhaps it is *unnecessary*?

 

[Steve Holden]

I had a structure that looked like this
((0,1), (2, 3), (4, 5), (6,7)

I changed my code slightly and now I do this:
odd = (1,3,5,7)
even = (0,2,4,6)
all = zip(even, odd)

however the zip produces:
[(0, 1), (2, 3), (4, 5), (6, 7)]

Which is a list of tuples.. I wanted a tuple of tuples...

So apply tuple() to the list!

all = tuple(zip(even, odd))

regards
Steve