Python - convert list of tuples to string

Question

Which is the most pythonic way to convert a list of tuples to string?

I have:

[(1,2), (3,4)]

and I want:

"(1,2), (3,4)"

My solution to this has been:

l=[(1,2),(3,4)]
s=""
for t in l:
    s += "(%s,%s)," % t
s = s[:-1]

Is there a more pythonic way to do this?

What are these tuples for, why do they need to be in a string, and do they in fact need to be tuples? — Ignacio Vazquez-Abrams
– Ignacio Vazquez-Abrams, Commented Jul 20, 2010 at 17:31
@Ignacio, @SilentGhost: I'd love to have you guys elaborate more on your comments (I'm still learning Python myself). It may not be an actual answer to OP's string formatting problem, but I'm sure you guys have very important points to make. — polygenelubricants
– polygenelubricants, Commented Jul 20, 2010 at 19:34
@polygenelubricants: Bottom line: there's no point to this. The tuple -- as a tuple -- is a fine structure. Why mess with it to make an obscurely formatted string? If all they want is a string, then the string.format method will do the job pretty simply. If they want something else, then the question should say what they're tying to accomplish. — S.Lott
– S.Lott, Commented Jul 20, 2010 at 20:22
@Ignacio Vazquez-Abrams, @SilentGhost: This string is the last part of a SQL query string: 'INSERT INTO table (field1, field) VALUES %s' % s. I know there are good frameworks out there like SQLAlchmey or Django, to do this kind of things, but I don't want to use it in this case. — ssoler
– ssoler, Commented Jul 21, 2010 at 7:59
Wait, what? You want to introduce SQL injection attacks into your code? Python gives you the tools to do it right and you want to go out of your way to do it wrong? I have no words. — Ignacio Vazquez-Abrams
– Ignacio Vazquez-Abrams, Commented Jul 21, 2010 at 8:11

mykhal · Accepted Answer · 2014-07-23 13:12:12Z

41

you might want to use something such simple as:

>>> l = [(1,2), (3,4)]
>>> str(l).strip('[]')
'(1, 2), (3, 4)'

.. which is handy, but not guaranteed to work correctly

edited Jul 23, 2014 at 13:12

answered Jul 20, 2010 at 17:34

mykhal

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5 Comments

Rob Lourens Over a year ago

What if the tuples are tuples of strings which contain []?

Ignacio Vazquez-Abrams Over a year ago

@Rob: str.strip() only removes from the ends.

Stephen Niedzielski Over a year ago

It seems like bad practice to rely on the internal string representation of a list.

GeoStoneMarten Over a year ago

@mykhal it cause some problem with unicode caracters

Yohan Obadia Over a year ago

Not going to work either if you want to join with a different separator.

polygenelubricants · Accepted Answer · 2010-07-20 17:49:11Z

39

You can try something like this (see also on ideone.com):

myList = [(1,2),(3,4)]
print ",".join("(%s,%s)" % tup for tup in myList)
# (1,2),(3,4)

edited Jul 20, 2010 at 17:49

answered Jul 20, 2010 at 17:30

polygenelubricants

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Comments

pillmuncher · Accepted Answer · 2010-07-20 19:13:07Z

21

How about:

>>> tups = [(1, 2), (3, 4)]
>>> ', '.join(map(str, tups))
'(1, 2), (3, 4)'

answered Jul 20, 2010 at 19:13

pillmuncher

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Comments

TylerH · Accepted Answer · 2023-10-20 08:15:16Z

2

I think the most Pythonic solution is

tuples = [(1, 2), (3, 4)]

tuple_strings = ['(%s, %s)' % tuple for tuple in tuples]

result = ', '.join(tuple_strings)

edited Oct 20, 2023 at 8:15

TylerH

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answered Jun 6, 2018 at 18:29

ValarDohaeris-fuck-OpenAI

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Comments

Benj · Accepted Answer · 2010-07-20 17:44:39Z

1

How about

l = [(1, 2), (3, 4)]
print repr(l)[1:-1]
# (1, 2), (3, 4)

answered Jul 20, 2010 at 17:44

Benj

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1 Comment

Benj Over a year ago

The spacing here isn't actually as you stipulated; if that's important, this approach won't work as python adds a space after each item in a list/tuple.

Maehler · Accepted Answer · 2012-07-03 07:50:04Z

1

I think this is pretty neat:

>>> l = [(1,2), (3,4)]
>>> "".join(str(l)).strip('[]')
'(1,2), (3,4)'

Try it, it worked like a charm for me.

edited Jul 3, 2012 at 7:50

Maehler

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answered Jul 3, 2012 at 7:10

luissanchez

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Comments

blaztinn · Accepted Answer · 2010-08-19 20:49:57Z

0

Three more :)

l = [(1,2), (3,4)]

unicode(l)[1:-1]
# u'(1, 2), (3, 4)'

("%s, "*len(l) % tuple(l))[:-2]
# '(1, 2), (3, 4)'

", ".join(["%s"]*len(l)) % tuple(l)
# '(1, 2), (3, 4)'

answered Aug 19, 2010 at 20:49

blaztinn

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