For-loops in Python
What is the best way of doing this in Python?
for (v = n / 2 - 1; v >= 0; v--)
I 开发者_StackOverflow中文版actually tried Google first, but as far as I can see the only solution would be to use while
.
I would do this:
for i in reversed(range(n // 2)):
# Your code
pass
It's a bit clearer that this is a reverse sequence, what the lower limit is, and what the upper limit is.
The way to do it is with xrange()
:
for v in xrange(n // 2 - 1, -1, -1):
(Or, in Python 3.x, with range()
instead of xrange()
.) //
is flooring division, which makes sure the result is a whole number.
for v in range(n//2, -1, -1)
However, in 90% of the cases when you would have used a for
loop in C/Java/C#/VB, what you really want is list comprehension:
listOfStuff = [doSomethingWith(v) for v in range(n//2, -1, -1)]
for v in xrange(n/2 - 1, 0, -1):
#your code here
Where v and n are int
s or treated as int
s. This means that the division will be an integer division, i.e., 1/2 == 0 is True
.
Note: This is for Python 2.x .
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