best way to do some simple tasks
marklists at mceahern.com
Thu Jan 30 00:46:55 CET 2003
> 1) String interpolation of lists and dictionaries
> What is the correct and best way to do this?
> x =[1,2,3,4]
> print "%(x)i blah" % vars() # <- does not work
print '%d blah' % x
lookup string formatting operations. Python doesn't have string
interpolation AFAIK, although there's been PEP(s?) for it.
> 2) Perform a method on each element of an array
> a= [" hello ", " there "]
> how do I use the string's strip() method on each element of the
> a = map((lambda s: s.strip()), a) # looks ugly to me
> for e in a: # this looks even worse
a = [x.strip() for x in a]
> 3) What is the best way to do this?
> how do I get c=a+b (c=[2,3,4])?
> If I wanted to use reduce(), how do I shuffle the lists?
c = map(operator.add, a, b)
> 4) Why does this work this way?
> for h in d:
> print d
> >>>[1, 2, 3, 4, 5]
> Is there a python reason why h is a copy not a reference to the
> element in the list? In perl the h would be a ref. If d was a tuple
> I could understand it working this way.
ints are immutable, lists aren't.
a = range(1,5)
b = [x+1 for x in a]
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