Import Error: can't import name gcd from fractions
Question:
I’m trying to import a function called gcd from a module called fractions with from fractions import gcd. For some reason, PyCharm throws an ImportError:
from fractions import gcd
ImportError: cannot import name 'gcd' from 'fractions'
I had this working before, what am I doing wrong?
Answers:
Your traceback says Python 3.9 and the documentation says
gcd is a function in math
Changed in version 3.9: The math.gcd() function is now used to
normalize the numerator and denominator. math.gcd() always return a
int type. Previously, the GCD type depended on numerator and
denominator.
It’s an issue with old networkx versions. Solve this updating networkx:
conda install -c conda-forge networkx=2.5
fractions.gcd(a, b) has been moved to math.gcd(a, b) in Python 3.9.
In fact it has been deprecated in Python 3.5 already (in brackets):
Python Version
fractions.gcd(a, b)math.gcd(a, b)math.gcd(*integers)
Python 3.0
X
Python 3.1
X
Python 3.2
X
Python 3.3
X
Python 3.4
X
Python 3.5
(X)
X
Python 3.6
(X)
X
Python 3.7
(X)
X
Python 3.8
(X)
X
Python 3.9
X
Python 3.10
X
Python 3.11
X
math.gcd can also take more than 2 arguments starting from 3.9, or even 0 or 1 argument.
if you want always at least the networkx version that works do:
conda install -y networkx">=2.5"
sometimes adding the -c conda-forge is useful…
Following will install the latest version of networkx:
conda install -c anaconda networkx
In Windows: cmd as administrator
pip unistall networkx
pip install networkx
I’m trying to import a function called gcd from a module called fractions with from fractions import gcd. For some reason, PyCharm throws an ImportError:
from fractions import gcd
ImportError: cannot import name 'gcd' from 'fractions'
I had this working before, what am I doing wrong?
Your traceback says Python 3.9 and the documentation says
gcd is a function in math
Changed in version 3.9: The math.gcd() function is now used to
normalize the numerator and denominator. math.gcd() always return a
int type. Previously, the GCD type depended on numerator and
denominator.
It’s an issue with old networkx versions. Solve this updating networkx:
conda install -c conda-forge networkx=2.5
fractions.gcd(a, b) has been moved to math.gcd(a, b) in Python 3.9.
In fact it has been deprecated in Python 3.5 already (in brackets):
| Python Version | fractions.gcd(a, b) |
math.gcd(a, b) |
math.gcd(*integers) |
|---|---|---|---|
| Python 3.0 | X | ||
| Python 3.1 | X | ||
| Python 3.2 | X | ||
| Python 3.3 | X | ||
| Python 3.4 | X | ||
| Python 3.5 | (X) | X | |
| Python 3.6 | (X) | X | |
| Python 3.7 | (X) | X | |
| Python 3.8 | (X) | X | |
| Python 3.9 | X | ||
| Python 3.10 | X | ||
| Python 3.11 | X |
math.gcd can also take more than 2 arguments starting from 3.9, or even 0 or 1 argument.
if you want always at least the networkx version that works do:
conda install -y networkx">=2.5"
sometimes adding the -c conda-forge is useful…
Following will install the latest version of networkx:
conda install -c anaconda networkx
In Windows: cmd as administrator
pip unistall networkx
pip install networkx