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?

Answer 1

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.

Answer 2

It's an issue with old networkx versions. Solve this updating networkx:

conda install -c conda-forge networkx=2.5

Answer 3

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.

Answer 4

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...

Answer 5

Following will install the latest version of networkx:

conda install -c anaconda networkx

Answer 6

In Windows: cmd as administrator

pip unistall networkx
pip install networkx