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Python Discussion Thread
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Nov 20th, 2005

Why a Set?

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I am making progress learning Python. and English. I understands tuples, lists and dictionaries, but sets don't make muchly sense. Why use a set? What is a set good for?

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bumsfeld

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Nearly a Posting Virtuoso

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Nov 20th, 2005

Re: Why a Set?

Hi!

Did you have a look at the python-docs?
This should make clear that sets are really useful

Regards, mawe

mawe

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Junior Poster

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Nov 20th, 2005

Re: Why a Set?

Thank you mawe,

so when I take the list with duplicates and make it one set then the duplicates are gone. How can I find out which were those duplicates?

bumsfeld

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Jan 9th, 2006

Re: Why a Set?

Quote originally posted by bumsfeld ...

Thank you mawe,

so when I take the list with duplicates and make it one set then the duplicates are gone. How can I find out which were those duplicates?

you can use the list method somelist.count(x),
which returns the number of i's for which somelist[i] == x :

Python Syntax (Toggle Plain Text)
l=list('a list of characterstrings')
for item in set(l):
	print item,'counted',l.count(item),'times'
l=list('a list of characterstrings')
for item in set(l):
	print item,'counted',l.count(item),'times'

gives

Python Syntax (Toggle Plain Text)
a counted 3 times
  counted 3 times
c counted 2 times
e counted 1 times
...
a counted 3 times
  counted 3 times
c counted 2 times
e counted 1 times
...

monkeyy

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Jan 9th, 2006

Re: Why a Set?

Thanks from the rest of us monkeyy! Great code!

vegaseat

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DaniWeb's Hypocrite

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Feb 10th, 2006

Re: Why a Set?

Yes, thanks monkeyy!

bumsfeld

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