Is there a ceiling equivalent of // operator in Python?
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I found out about the
// operator in Python which in Python 3 does division with floor.
Is there an operator which divides with ceil instead? (I know about the
/ operator which in Python 3 does floating point division.)
There is no operator which divides with ceil. You need to
import math and use
Is there a ceiling equivalent of // operator in Python?, There is no operator which divides with ceil. You need to import math and use math.ceil. Python number method ceil() returns ceiling value of x - the smallest integer not less than x. Syntax. Following is the syntax for ceil() method − import math math.ceil( x ) Note − This function is not accessible directly, so we need to import math module and then we need to call this function using math static object. Parameters
You can just do upside-down floor division:
def ceildiv(a, b): return -(-a // b)
This works because Python's division operator does floor division (unlike in C, where integer division truncates the fractional part).
This also works with Python's big integers, because there's no (lossy) floating-point conversion.
Here's a demonstration:
>>> from __future__ import division # a/b is float division >>> from math import ceil >>> b = 3 >>> for a in range(-7, 8): ... print(["%d/%d" % (a, b), int(ceil(a / b)), -(-a // b)]) ... ['-7/3', -2, -2] ['-6/3', -2, -2] ['-5/3', -1, -1] ['-4/3', -1, -1] ['-3/3', -1, -1] ['-2/3', 0, 0] ['-1/3', 0, 0] ['0/3', 0, 0] ['1/3', 1, 1] ['2/3', 1, 1] ['3/3', 1, 1] ['4/3', 2, 2] ['5/3', 2, 2] ['6/3', 2, 2] ['7/3', 3, 3]
floor() and ceil() function Python, The method ceil() in Python returns ceiling value of x i.e., the smallest integer not less than x. Syntax: import math math.ceil(x) Parameter: x:This is a numeric r/Python: news about the dynamic, interpreted, interactive, object-oriented, extensible programming language Python
You could do
(x + (d-1)) // d when dividing
(x + 4) // 5.
Is there a ceiling equivalent of // operator in Python?, Is there an operator which divides with ceil instead? (I know about the / operator which in Python 3 does floating point division.) All Answers. Annabelle Lee #1. The method ceil () in Python returns ceiling value of x i.e., the smallest integer not less than x. Syntax: import math math.ceil (x) Parameter: x:This is a numeric expression. Returns: Smallest integer not less than x. Below is the Python implementation of ceil () method: # Python program to demonstrate the use of ceil () method.
You can always just do it inline as well
((foo - 1) // bar) + 1
In python3, this is just shy of an order of magnitude faster than forcing the float division and calling ceil(), provided you care about the speed. Which you shouldn't, unless you've proven through usage that you need to.
>>> timeit.timeit("((5 - 1) // 4) + 1", number = 100000000) 1.7249219375662506 >>> timeit.timeit("ceil(5/4)", setup="from math import ceil", number = 100000000) 12.096064013894647
Python ceil Function, The Python ceil function is one of the Python Math function used to return the smallest integer value, which is greater than or equal to the specified expression or a specific number. In this section, we If the number argument is a positive or negative number, the ceil function returns the ceiling value. Java Ternary Operator. By the way, in Python 3.x, math.ceil works exactly as you want it to, except that it returns an int rather than a Decimal instance. That works because math.ceil is overloadable for custom types in Python 3.
Solution 1: Convert floor to ceiling with negation
def ceiling_division(n, d): return -(n // -d)
Reminiscent of the Penn & Teller levitation trick, this "turns the world upside down (with negation), uses plain floor division (where the ceiling and floor have been swapped), and then turns the world right-side up (with negation again)"
Solution 2: Let divmod() do the work
def ceiling_division(n, d): q, r = divmod(n, d) return q + bool(r)
The divmod() function gives
(a // b, a % b) for integers (this may be less reliable with floats due to round-off error). The step with
bool(r) adds one to the quotient whenever there is a non-zero remainder.
Solution 3: Adjust the numerator before the division
def ceiling_division(n, d): return (n + d - 1) // d
Translate the numerator upwards so that floor division rounds down to the intended ceiling. Note, this only works for integers.
Solution 4: Convert to floats to use math.ceil()
def ceiling_division(n, d): return math.ceil(n / d)
The math.ceil() code is easy to understand, but it converts from ints to floats and back. This isn't very fast and it may have rounding issues. Also, it relies on Python 3 semantics where "true division" produces a float and where the ceil() function returns an integer.
Python Number ceil() Method, Python number method ceil() returns ceiling value of x - the smallest integer not less than x. Syntax. Following is the syntax for ceil() method − import math math. Ternary Operator in Python; Increment and Decrement Operators in Python; Python | Set 2 (Variables, Expressions, Conditions and Functions) Python | Set 3 (Strings, Lists, Tuples, Iterations) Project Idea | (A Game of Anagrams ) Print Single and Multiple variable in Python; Swap two variables in one line in C/C++, Python, PHP and Java
Python 3 - Number ceil() Method, The ceil() method returns the ceiling value of x i.e. the smallest integer not less than x. Syntax. Following is the syntax for the ceil() method − import math math.ceil( Python is a lot about clarity and no programmer is likely to correctly guess the meaning of --a unless s/he's learned a language having that construct. Python is also a lot about avoiding constructs that invite mistakes and the ++ operators are known to be rich sources of defects. These two reasons are enough not to have those operators in Python.
9.2. math — Mathematical functions, Return the ceiling of x as a float, the smallest integer value greater than or equal to x. math. copysign (x, y)¶. Return x with the sign of y Operators are the constructs which can manipulate the value of operands. Consider the expression 4 + 5 = 9. Here, 4 and 5 are called operands and + is called operator. Python language supports the following types of operators.
Test your skills in Python Language: A complete questionnaire for , the ceiling value 24 math.floor(23.5) returns the floor value 23 math.sqrt(25) returns square root of 25 in double 5.0 There are three logical operators in Python: Many operations have an “in-place” version. Listed below are functions providing a more primitive access to in-place operators than the usual syntax does; for example, the statement x += y is equivalent to x = operator.iadd(x, y). Another way to put it is to say that z = operator.iadd(x, y) is equivalent to the compound statement z = x; z += y.
- Important: do you want an int or float result?
- You should change accepted answer to dlitz's. math.ceil is for floats, it does not work with Python's arbitrary-precision long ints.
- @milllimoose The question is valid, because 1) "ceil division" is also based on "division with modulus", 2) math doesn't really say what's common and what isn't, 3) you need this operation for "continuous bin packing problem", i.e. how many boxes of size $k$ are neeeded to pack $n$ items.
- so foobar = math.ceil(foo / bar)? Hmm, I can live with that, don't know of anywhere I wanted to use that, was just curious, thanks
- –1 do not use, this will begin to fail for very large integers. Either use a multiple-precision arithmetic library or stay in the integer domain with this approach.
- definitely stay in the integer domain. that's almost guaranteed to be more performant and less of a headache.
- @David天宇Wong gmpy2 (mentioned in another answer here) is good.
- Note that math.ceil is limited to 53 bits of precision. If you are working with large integers, you may not get exact results.
- @apadana I agree this is very smart, but not very readable and hard to maintain! I have decided to import ceil from math so that when one of my colleagues reads my line of code he will understand what it does!
- @apadana I disagree. The question asked whether there "is" an operator for this "in" Python. Based on the responses, the answer appears to be "no." I'm upvoting dlitz's answer for its usefulness, though.
- @SlimCheney Toss this method into a documented function and you're good to go. Performance + readability in one sweeping motion.
- @SamyBencherif: Not just performance + readability, but also correctness for large inputs; floating point has representation limitations, while Python's
intdoes not (well, no meaningful ones; on 64 bit Python you're limited to
30 * (2**63 - 1)bit numbers), and even temporarily converting to
floatcan lose information. Compare
math.ceil((1 << 128) / 10)to
-(-(1 << 128) // 10).
- This should just be included in standard library
- This is the classic method I've used forever. Doesn't work for negative divisors though.