从我自己的目录运行Python时，为什么Python无法运行该程序？

Question

This is not working:

numbers is a directory:

$ cat numbers.py
import networkx as nx


~/numbers $ python2.7 < numbers.py

This gives me a few errors which end with something like:

'module' object has no attribute 'Number'

This is working:

~ $ python2.7 < numbers/numbers.py

I installed networkx following these instructions: http://networkx.github.io/documentation/latest/install.html

Download the source (tar.gz or zip file) from https://pypi.python.org/pypi/networkx/ or get the latest development version from https://github.com/networkx/networkx/
Unpack and change directory to the source directory (it should have the files README.txt and setup.py).
Run python setup.py install to build and install
(Optional) Run nosetests to execute the tests if you have nose installed.

The tests run fine, but I don't understand why the trivial program containing only "import networkx as nx" won't run.

What is the difference between these two situations ?

Answer 1

You are passing in the script on STDIN, instead of on the command line, so Python adds the current working directory to sys.path instead of numbers .

Normally, Python adds the directory of the script as first element in sys.path :

As initialized upon program startup, the first item of this list, path[0] , is the directory containing the script that was used to invoke the Python interpreter. If the script directory is not available (eg if the interpreter is invoked interactively or if the script is read from standard input), path[0] is the empty string, which directs Python to search modules in the current directory first.

If you are having import problems, then it sounds as if the wrong module is being imported; perhaps you are masking a stdlib module with one with the same name, locating in numbers . Rename that module.