sorting a list of tupples

[David Bear]

I have a list of tupples. Each tupple has 3 items. The first item is
an integer. I'd like to sort the list(of tupples), based on the first
element of the tupple. I thought about stringifying the tupples, then sorting
those, but thought there must be a better way. any idea's?

--David Bear
phone: 480-965-8257
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College of Public Programs/ASU
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[John Roth]

I have a list of tupples. Each tupple has 3 items. The first item is
an integer. I'd like to sort the list(of tupples), based on the first
element of the tupple. I thought about stringifying the tupples, then sorting
those, but thought there must be a better way. any idea's?

<list>.sort() should do the job, as long as you want the result
to be a list in ascending order by the value of the first element
of the tuple.

John Roth

 

[Daniel Luz]

I have a list of tupples. Each tupple has 3 items. The first item is
an integer. I'd like to sort the list(of tupples), based on the first
element of the tupple. I thought about stringifying the tupples, then sorting
those, but thought there must be a better way. any idea's?

Have you tried just sort()ing the list? Tuples naturally will sort based
on the first element of them (then, if two elements are equal, it will
try to sort based on the second element, and so forth).

>>> l = [(1, 'p'), (6, 'n'), (4, 'h'), (3, 't'), (5, 'o'), (2, 'y')]
>>> l.sort()
>>> l

[(1, 'p'), (2, 'y'), (3, 't'), (4, 'h'), (5, 'o'), (6, 'n')]


If that's not what you meant, could you please clarify?

 

[Stephen Horne]

I have a list of tupples. Each tupple has 3 items. The first item is
an integer. I'd like to sort the list(of tupples), based on the first
element of the tupple. I thought about stringifying the tupples, then sorting
those, but thought there must be a better way. any idea's?

You can sort a list of tuples using the standard sort method. Ordering
of tuples is derived much like ordering of strings - it will use the
order of the first items in the tuples unless they are equal in which
case it uses the second items, or third items, or whatever. If all
else fails, the longest tuple is considered greater.

If you are sorting on the first item, the sort method should just work
for you.

 

[Dave Kuhlman]

<list>.sort() should do the job, as long as you want the result
to be a list in ascending order by the value of the first element
of the tuple.

And, if you don't want to sort on the first element or want to
sort in descending order or ... you will want to know about the
optional argument to the sort method. You can pass it your own
custom comparison function. Read about it here:

http://www.python.org/doc/current/lib/typesseq-mutable.html

The info you (might) want is down in a footnote.

Dave