No swap function in Python?

Bernhard Herzog bh at intevation.de
Wed May 30 17:46:52 CEST 2001


Pierre Barn <pbarn at altern.org> writes:

> in article 3B150A65.5D4986FC at europem01.nt.com, Bolton, Gawain
> [ADC:4808:EXCH] at boltong at europem01.nt.com wrote on 30/05/01 16:57:
> 
> > Which made me think that a swap could be done like this:
> > 
> > (a,b) = (b,a)
> 
> You can do a, b = b, a
> As you discovered.
> 
> > is this an efficient
> > way of doing a swap?
> 
> It is

Well, if a and b are local variables, the more traditional idiom
temp = a; a = b; b = temp
is a tad faster, at least on my machine, because a, b = b, a actually
constructs the intermediate tuple object.

Of course, a, b = b, a is much easier to read, which outweighs the
minuscule speed advantage of the other form.

  Bernhard

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