打印没有括号的元组列表python

Question

I have a list of tuples and I want to print flattened form of this list. I don't want to transform the list, just print it without parenthesis and brackets.

input: [ ("a", 1), ("b",2), ("c", 3)]
output:   a 1 b 2 c 3

Here's what I do:

l = [ ("a", 1), ("b",2), ("c", 3)]
f = lambda x: " ".join(map(str,x))
print " ".join(f(x) for x in l)

I'm interested in if anybody has a more elegant and possibly a more efficient solution,possibly without doing join, only print. Thanks in advance.

Answer 1

from __future__ import print_function 

l =  [("a", 1), ("b",2), ("c", 3)]

print(*(i for j in l for i in j))
a 1 b 2 c 3

Or using itertools.chain to flatten:

from itertools import chain

print(*chain(*l))

Answer 2

Using str.join() you can use a nested list comprehension:

>>> print ' '.join([str(i) if isinstance(i,int) else i for tup in A for i in tup])
a 1 b 2 c 3

And without join() still you need to loop over the the items and concatenate them, which I think join() is more pythonic way for this aim.

Answer 3

If you absolutely have to do this without list flattening operations like join , then this will work, but it's terrible and you should just use join :

[sys.stdout.write(str(i) + ' ' + str(j) + ' ') for (i, j) in input]

Using stdout.write because it does not automatically append a newline like print does.

Answer 4

That's more simple than you can imagine.

   a = [ ("a", 1), ("b",2), ("c", 3)]
    for i,j in a:
        print(i,j,end=' ')