I'm trying to use a function called start to set up my enviroment in python. The function imports os.
After I run the function and do the following
os.listdir(simdir+"main")
I get a error that says os not defined
code
>>> def setup ():
import os.path
import shutil
simdir="e:\\"
maindir="c:\\backup\\bitcois\\test exit\\"
>>> setup()
>>> os.listdir(simdir+"main")
Traceback (most recent call last):
File "<pyshell#10>", line 1, in <module>
os.listdir(simdir+"main")
NameError: name 'os' is not defined
The import statement is scoped. When importing modules they are defined for the local namespace.
From the documentation:
Import statements are executed in two steps: (1) find a module, and initialize it if necessary; (2) define a name or names in the local namespace (of the scope where the import statement occurs). [...]
So in your case the os package is only defined within function setup.
You are getting this error because you are NOT importing the whole os library but just the os.path module. In this way, the other resources at the os library are not made available for your use.
In order to be able to use the os.listdir method, you need to either import it alongside the os.path like this:
>>> def setup ():
import os.path, os.listdir
import shutil
simdir="e:\\"
maindir="c:\\backup\\bitcois\\test exit\\"
or import the full library:
>>> def setup ():
import os
import shutil
simdir="e:\\"
maindir="c:\\backup\\bitcois\\test exit\\"
You can read more here:
https://docs.python.org/2/tutorial/modules.html
try:
import os.path
import shutil
import glob
def setup ():
global simdir
simdir="e:\\"
maindir="c:\\backup\\bitcois\\test exit\\"
setup()
os.listdir(simdir+"main")
You need to return the paths and assign the returned values in the global scope. Also, import os too:
import os
def setup():
# retain existing code
return simdir, maindir
simdir, maindir = setup()
When you import os or do any sort of command within a function, the command's effect only last while that function itself is running. What you need to do is
import os
...Do your function and other code
This way, your import lasts for the whole program :).
Related
below the folder structure of my software:
below the code of all the .py files:
run.py:
import modules.module_01.aa as a
a.test()
# test:
if __name__=="__main__":
pass
aa.py (module 1):
import libraries.qq as q
import libraries.zz as z
def test():
q.qq_fun()
z.zz_fun()
print("ciao")
qq.py (library used by aa.py):
def qq_fun():
pass
zz.py (library used by aa.py):
def zz_fun():
pass
my question is really simple, why when I run "run.py" Python say to me:
why "aa.py" can't import the module "qq.py" and "zz.py"? how can I fix this issue?
run.py
In run.py, the Python interpreter thinks you're trying to import module_01.aa from a module named module. To import aa.py, you'll need to add this code to the top of your file, which adds the directory aa.py is in to the system path, and change your import statement to import aa as a.
import sys
sys.path.insert(0, "./modules/module_01/")
aa.py
The same problem occurs in aa.py. To fix the problem in this file, you'll need to add this code to the top of aa.py, which adds the directory qq.py and zz.py are in, and remove the libraries. from both of your import statements.
import sys
sys.path.insert(0, "./modules/module_01/libraries")
e.g.
import os as my_os
import my_os.path
ModuleNotFoundError: No module named 'my_os'
but the following script is ok
import os
import os.path
You can't do that in Python.
import statements are importing from Python file names.
You aren't renaming the file of os to my_os, therefore this wouldn't work.
As mentioned in the documentation:
The import statement combines two operations; it searches for the named module, then it binds the results of that search to a name in the local scope.
Tried the similar way as os.py did:
import json as my_json
from my_json.decoder import * # ModuleNotFoundError: No module named 'my_json'
import sys
import json.decoder as my_decoder
sys.modules['my_json.decoder'] = my_decoder
from my_json.decoder import * # it's ok now
I have a package structure like this:
- src
- src/main.py
- src/package1
- src/package1/__init__.py
- src/package1/module1.py
- src/package1/module2.py
... where module2 is a subclass of module1, and therefore module1 gets referenced by an absolute import path in module2.py.
That is, in src/package1/module2.py:
from package1.module1 import SomeClassFromModule1
The problem occurs in the main.py script:
## here the imports
def main():
# create an instance of the child class in Module2
if __name__ == "__main__":
main()
Option 1 works. That is, in src/main.py:
from package1.module2 import SomeClassFromModule2
some_name = SomeClassFromModule2()
Option 2 does not work. That is, in src/main.py:
import package1.module2.SomeClassFromModule2
some_name = package1.module2.SomeClassFromModule2()
... causes the following error.
ModuleNotFoundError: No module named 'package1.module2.SomeClassFromModule2'; 'package1.module2' is not a package
So why is there this difference between the import and from ... import idiom?
Would be glad for some clarification.
import x keyword brings all the methods and class from x in the the file it is being called.
from x import y this brings a specific method or class('y' is a method or class) from that .py file ('x' is the file here) instead of bringing all the methods it has.
In your case when you import package1.module2 the SomeClassForModule2() is being already imported and hence you need not write import package1.module2.SomeClassFromModule2
here I guess you want to access a class, so you need to create a object in order to access it.
hope this helped you
After some test, I think you cannot import a function or class by using import your_module.your_class.
It's all about package, module, function and class:
# import module
>>>import os
<module 'os' from ooxx>
#use module of module (a litte weird)
>>>os.path
<module 'posixpath' from ooxx>
#import module of module (a litte weird)
>>>import os.path
#use function
>>>os.path.dirname
<function posixpath.dirname(p)>
# you cannot import a function (or class) by using 'import your.module.func'
# 'import ooxx' always get a module or package.
>>>import os.path.dirname
ModuleNotFoundError
No module named 'os.path.dirname'; 'os.path' is not a package
# instead of it, using 'from your_module import your_function_or_class'
>>>from os.path import dirname
<function posixpath.dirname(p)>
I have three files under the same directory, namely, main.py, Newtester.py, and fileUtility.py. In Newtester.py there is a class named Function. In main.py, there are the following codes:
from file.py import *
...
def main():
...
funcs = parseFuncSpec(funcInputFile)
parseFuncSpec is defined in fileUtilities.py as:
some code to import Newtester.py
def parseFuncSpec(fName):
curFunc = function(funcName, numTest, [], score)
Regardless of what I put in import Newtester.py, I always get an error saying "Function" (the class defined in the file "Newtester.py") is not defined. Following Python: How to import other Python files, I have attempted
import Newtester
__import__("Newtester")
exec("Newtester.py")
exec("Newtester")
import importlib
importlib.__import__("Newtester")
os.system("Newtester.py")
But none of them seemed to work. Any advice is appreciated. See https://github.com/r2dong/unitTesting if you are interested in seeing the complete files.
It's because you are not using it correctly
well when you use import statement like below only Newstester file is imported
import Newtester
hence instead of using parseFuncSpec() directly you have to use it as Newtester.parseFuncSpec()
or to use parseFuncSpec() directly you need to use below import statement:
from Newtester import parseFuncSpec
I failed to import a module from sub directory in python. Below is my project structure.
./main.py
./sub
./sub/__init__.py
./sub/aname.py
when I run python main.py, I got this error:
Traceback (most recent call last):
File "main.py", line 4, in <module>
import sub.aname
File "/Users/dev/python/demo/sub/__init__.py", line 1, in <module>
from aname import print_func
ModuleNotFoundError: No module named 'aname'
I don't know it failed to load the module aname. Below is the source code:
main.py:
#!/usr/bin/python
import sub.aname
print_func('zz')
sub/__init__.py:
from aname import print_func
sub/aname.py:
def print_func( par ):
print ("Hello : ", par)
return
I am using python 3.6.0 on MacOS
There are several mistakes in your Python scripts.
Relative import
First, to do relative import, you must use a leading dots (see Guido's Decision about Relative Imports syntax).
In sub/__init__.py, replace:
from aname import print_func
with:
from .aname import print_func
Importing a function
To import a function from a given module you can use the from ... import ... statement.
In main.py, replace:
import sub.aname
with:
from sub import print_func
from sub import aname
aname.print_func('zz')
Probably the most elegant solution is to use relative imports in your submodule sub:
sub.__init__.py
from .aname import print_func
But you also need to import the print_func in main.py otherwise you'll get a NameError when you try to execute print_func:
main.py
from sub import print_func # or: from sub.aname import print_func
print_func('zz')