Difference in formatting list and tuple values
Dr. Des Small
des.small at bristol.ac.uk
Thu Dec 13 12:25:17 EST 2001
sag at hydrosphere.com (Sue Giller) writes:
> I am trying to format values from either a list or a tuple, and I am
> getting the following odd (to me) behavior.
Well, you're doing an odd (to me) thing...
> I can format the tuple
> entry using %d, but I get an error when I use the same formatting
> for the same data in a list.
> Why does this happen?
> >>> print "%02d" % l[:1] # get error with list
> Traceback (most recent call last):
> File "<interactive input>", line 1, in ?
> TypeError: an integer is required
> >>> print "%02d" % tuple(t[:1]) # cast to a tuple works ok
The right hand side of the % operator must be either a tuple or a
single item. I would probably write
print "%02d" % t
to do this, since it works for both lists and tuples. But if you're
secretly doing something fancy like
print len(l)*"%02d " % tuple(l)
then you will need the cast. The only weirdness here is that % doesn't
single elements to be tuplified, which is a concession to
print "%d" % (12,)
is also legal, but a little peculiar to look at.
Dr Des Small, Scientific Programmer,
School of Mathematics, University of Bristol,
Tel: 0117 9287984
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