I have a problem that runs like this:
I have an integer n, let n = 30, and a given range of numbers x and y that x < y, say 20 and 35.
I add n with another integer k. Say, k = 19.
However, I want to keep n between x and y. So if n+k > 35 it jumps back to 20 at 36, then continue to add 13 (19-6=13), which the final answer is 33.
I have already done the problem from scratch, and it's lengthy. It looks like this:
def plus(n,k,x,y):
result = n+k
if result > y: #do sth
if result < x: #do sth
return result
My question is, is there any build-in method, in any library, that helps me to do this problem? Thanks a lot.
The modulo operator % performs the kind of wrapping you're looking for. a % b gives the remainder from dividing a by b, resulting in the following wraparound pattern:
>>> for i in range(-2, 12):
... print(f"{i} % 5 = {i % 5}")
...
-2 % 5 = 3
-1 % 5 = 4
0 % 5 = 0
1 % 5 = 1
2 % 5 = 2
3 % 5 = 3
4 % 5 = 4
5 % 5 = 0
6 % 5 = 1
7 % 5 = 2
8 % 5 = 3
9 % 5 = 4
10 % 5 = 0
11 % 5 = 1
(The results you see with a negative left operand aren't what you get in most languages. Most languages would give you -2 and -1 instead of 3 and 4, but the 3 and 4 answers turn out to be more useful.)
You want to stay in a range from x to y inclusive instead of 0 to y-1, so we need to add and subtract x to adjust the range % gives us:
def plus(n,k,x,y):
modulus = y-x+1
return (n+k-x) % modulus + x
Sample output:
>>> plus(30, 19, 20, 35)
33
>>> plus(30, 0, 20, 35)
30
>>> plus(30, 5, 20, 35)
35
>>> plus(30, 6, 20, 35)
20
>>> plus(30, -10, 20, 35)
20
>>> plus(30, -11, 20, 35)
35