I'm a Java guy, currently learned Python. I'm stuck on how to use multiple conditions inside the Python for-loop.
here is the Java code
for (int r = n-1, s = k+1; r > s; r--, s++)
// some code
How can I convert this into Python for-loop?
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There is only for-in-loops in Python, you may generate a lazy sequence of all possibilities of rzwlxt– zwlxt2021-01-19 02:39:32 +00:00Commented Jan 19, 2021 at 2:39
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2 Answers
This can best be implemented as a while loop. It is more verbose than Java but also more Pythonic and, in my personal opinion, more readable:
r = n - 1
s = k + 1
while r > s:
# some code
r -= 1
s += 1
Update: You can use a for loop but it's not as pretty:
p = (k + n) // 2
for r, s in zip(range(n - 1, p, -1), range(k + 1, p + 1)):
# some code
1 Comment
frankiie
thanks for your comment! I have another question. Is there any way to performs this task by using for-loop?
If you insist on doing it with a for loop, you can create a generator:
def gen(n, k):
r = n - 1
s = k + 1
while r > s:
yield (r, s)
r -= 1
s += 1
for x in gen(n, k):
#some code
#alternatively:
for x, y in gen(n, k):
#some code
4 Comments
mhawke
Great idea, but: the generator should yield the tuple
(r, s) so that these can be treated as loop variables, i.e. the consuming code would be for r,s in gen(n, k). Also, the yield r, s should be before the increment and decrement of variables so that the first values mimic that of a for loop.
pakpe
@mhawke You are absolutely right. I modified my code.
mhawke
I'd still change it to
for r, s in gen(n, k) but that's up to the consumer to decide,pakpe
@mhawke Right. Done!