What function has these integer results?

Question

For example, I have a reference number a = 15 and b= 3.

If x=2, f(a,b,x) = 1 because if one divide 15 into 3 parts, the number 2 is in the first part.
If x=7, f(a,b,x) = 2 because if one divide 15 into 3 parts, the number 7 is in the second part.
If x=15, f(a,b,x) = 3 because if one divide 15 into 3 parts, the number 15 is in the third part.
If x<0 or >15 the results are irrelevant to me.

Is there any built-in function like this?

You could subtract `x` from `a` and divide by `b` (truncated), I think you'd get your answer, except zero-indexed. — Waleed Khan, Mar 10 '14 at 19:51
Four upvotes for question about simple arithmetic one-liner? Really? — aga, Mar 10 '14 at 19:58
If x <= (a//b)*c the answer is c. That is, if x <= 5*1, the answer is 1. If x <= 5*2, it's 2 and so on. — David Sousa, Mar 10 '14 at 19:59
aga, the question is about a built-in function and not about how to write a function. — David Sousa, Mar 10 '14 at 20:00
@David: That's a resource request and off-topic then; and not all that useful a question to answer. Such a function is not commonly needed in general Python programming, nor is it a common function in mathematics. Why would you expect it to be built-in? — Martijn Pieters, Mar 10 '14 at 20:00
@MartijnPieters that function seems useful to me, so I expected that it would exist. — David Sousa, Mar 10 '14 at 20:04
@DavidSousa: Many functions are useful to many, but still not generally applicable. — Martijn Pieters, Mar 10 '14 at 20:05

NPE · Answer 1 · 2014-03-10T19:59:34.683

7

I can't think of a single built-in function which would do exactly that. It is however not difficult to write one:

def f(a, b, x):
  return (x - 1) * b // a + 1

for i in range(1, 16):
  print i, f(15, 3, i)

This prints out

(It is not entirely clear from the question how, and if, x=0 needs to be handled; this answer considers it to be outside the valid range.)

edited Mar 10 '14 at 19:59

answered Mar 10 '14 at 19:54

NPE

score 1 · Answer 2 · answered Mar 10 '14 at 19:52

1

No, there is no such built-in function. You can certainly write your own, however.

answered Mar 10 '14 at 19:52

Scott Hunter

2

Although true, this could have been a comment; why not *write that function*? As it stands, this isn't very helpful. – Martijn Pieters Mar 10 '14 at 19:53
1

OP didn't ask for a function definition; explicitly asked for a built-in one. Thus, this is PRECISELY answering the question as asked. – Scott Hunter Mar 10 '14 at 19:54
2

Yup, but that means, in my experience, that the OP is really asking for such a function. If there is no such function, *why* isn't there; is it impossible to write it? Etc. A simple 'no, there is not' is rarely actually helpful. – Martijn Pieters Mar 10 '14 at 19:58
1

And yet the author comments above "aga, the question is about a built-in function and not about how to write a function." – Scott Hunter Mar 10 '14 at 20:10

2 Answers2