Python 替换已弃用的`fractions.gcd()`函数?
我想计算两个有理数的最大公约数,这两个有理数被实现为Python 替换已弃用的`fractions.gcd()`函数?,python,python-3.x,fractions,Python,Python 3.x,Fractions,我想计算两个有理数的最大公约数,这两个有理数被实现为分数.Fraction实例。尽管打印了弃用警告,但它仍按预期工作: In [1]: gcd(Fraction(2, 3), Fraction(2, 3)) /usr/local/bin/ipython:1: DeprecationWarning: fractions.gcd() is deprecated. Use math.gcd() instead. #!/usr/local/opt/python3/bin/python3.6 Out[
分数.Fraction
实例。尽管打印了弃用警告,但它仍按预期工作:
In [1]: gcd(Fraction(2, 3), Fraction(2, 3))
/usr/local/bin/ipython:1: DeprecationWarning: fractions.gcd() is deprecated. Use math.gcd() instead.
#!/usr/local/opt/python3/bin/python3.6
Out[1]: Fraction(1, 6)
通过查看,我可以看到fracts.gcd()
确实不受欢迎,用户被邀请使用math.gcd()
。问题在于后者不支持有理数:
In [2]: gcd(Fraction(2, 3), Fraction(2, 3))
---------------------------------------------------------------------------
TypeError Traceback (most recent call last)
<ipython-input-2-c3ad2389f290> in <module>()
----> 1 gcd(Fraction(2, 3), Fraction(2, 3))
TypeError: 'Fraction' object cannot be interpreted as an integer
公式在这里推导和解释:。您可能需要编写一个公式
gcd(a/b,c/d)=gcd(a,c)/lcm(b,d)
,所以这并不太糟糕math
不提供lcm
,因此我使用的是编写的
由于您似乎正在使用未记录的
分数.gcd()
(文档中说“返回整数a和b的最大公约数”),因此可能没有公约数。您是对的,我错过了!从我在实际实现()中看到的情况来看,这绝对不是预期的行为。。。谢谢我会考虑<代码>分数。GCd()/Cord>将分数作为预期行为……你的公式没有意义;code>denom_lcm是一个元组
def gcd(numbers):
"""Compute Greastest Common Divisor of rational numbers.
Args:
numbers: list of rational numbers.
Returns:
Greatest Common Divisor of rational numbers.
"""
# Treat the two-number case and reduce
def _gcd(a, b):
if b == 0:
return a
if isinstance(a, int) and isinstance(b, int):
_gcd(b, a % b)
a = Fraction(a)
b = Fraction(b)
return Fraction(gcd([a.numerator, b.numerator]), lcm([a.denominator, b.denominator]))
return reduce(_gcd, numbers)
def lcm(numbers):
"""Compute Least Common Multiple of rational numbers.
Args:
numbers: list of rational numbers.
Returns:
Least Common Multiple of rational numbers.
"""
# Treat the two-number case and reduce
def _lcm(a, b):
if b == 0:
return a
if isinstance(a, int) and isinstance(b, int):
return a * b // gcd([a, b])
a = Fraction(a)
b = Fraction(b)
return Fraction(lcm([a.numerator, b.numerator]), gcd([a.denominator, b.denominator]))
return reduce(_lcm, numbers)
from fractions import Fraction
from math import gcd
def lcm(a, b):
"""Return lowest common multiple."""
return a * b // gcd(a, b)
def fraction_gcd(x, y):
a = x.numerator
b = x.denominator
c = y.numerator
d = y.denominator
return Fraction(gcd(a, c), lcm(b, d))
print(fraction_gcd(Fraction(2, 3), Fraction(2, 3)))
# 2/3