Have a look at the error in the attached scrren shot.
new is the directory which contains unittest module of python 3.6 and new2 contains unittest module of python 2.7. I understand the error raised in first case is because of missing StringIO module. But why python 2.7 is raising error despite writing the same command as in python 3. Is the syntax different in the two cases?
Does this help?:
import sys
sys.path.append('path/to/your/file')
import your.lib
You need an __init.__py file. See here: https://docs.python.org/2/tutorial/modules.html#packages
The init.py files are required to make Python treat the directories as containing packages; this is done to prevent directories with a common name, such as string, from unintentionally hiding valid modules that occur later on the module search path. In the simplest case, init.py can just be an empty file, but it can also execute initialization code for the package or set the all variable, described later.
Related
Okay, so in the past, I've made my own Python packages with Python 2.x (most recently, 2.7.5). It has worked fine. Let me explain how I did that, for reference:
Make a directory within the working directory. We'll call it myPackage.
Make a file called __init__.py in the directory myPackage.
Make sure all the modules that you want to be part of the package are imported within __init__.py. These modules are typically in the myPackage folder.
From a Python program in the working directory, type import myPackage (and it imports fine, and is usable).
However, in Python 3, I get errors with that. (ImportError: No module named 'Whatever the first imported module is')
I researched the problem and found the following:
Starred imports don't work in Python 3.3.
The __init__.py file is not required in Python 3.3.
So, I removed the stars from my imports, and leaving the __init__.py file in, I still got errors (ImportError: No module named 'Whatever the first imported module is'). So, I removed the __init__.py file, and I don't get any errors, but my package doesn't include any of my modules.
Okay, so I discovered by doing a web search for python3 __init__.py or some such that I can do the following, although I don't have any clue if this is the standard way of doing things:
In the modules in the package, make sure there are no plain imports (not just no starred ones). Only do from myModule import stuff. However, you need to put a . in front of myModule: e.g. from .myModule import stuff. Then, I can import myPackage.oneOfMyModules
I found that by following this rule in the __init__.py file, it also works.
Once again, I don't know if this is how it's supposed to work, but it seems to work.
I found this page that is supposed to have something to do with the changes in packages in Python 3.something, but I'm not sure how it relates to what I'm doing:
http://legacy.python.org/dev/peps/pep-0420/
So, what is the standard way to do this? Where is it documented (actually saying the syntax)? Is the way I'm doing it right? Can I do regular imports instead of from package import module?
After analyzing some Python 3 packages installed on my system (I should have tried that to start with!) I discovered that they often seem to do things a little differently. Instead of just doing from .myModule import stuff they would do from myPackage.myModule import stuff (inside the modules in the package). So, that works, too, I suppose, and seems to be more frequently used.
I'm following a tutorial to call python code from a C++ program from the python docs.
Everything works just fine when trying to call the multiply example. Now if I add a line to the python source code importing a library, lets say openpyxl,
from openpyxl import load_workbook
I receive an error from python
ImportError: No module named openpyxl
I thought if I import a system library, I wouldn't have any problems, but I also get an error if I try to import datetime.
I don't have any error if I import the file from the python console. The openpyxl library is installed in my system.
So my question is: how to import python source code that needs to import packages?
EDIT: Ok, I forgot to mention something, I have not been completely honest with you guys, I'm sorry.
Trying to run the example I run into a problem: I couldn't make python found my multiply.py file, and the line PyImport_Import always return null.
My solution was to add the path in which I knew my python source was by using PySys_SetPath. The problem is that I just realized that this function doesn't append a new directory, it just overwrites the PYTHONPATH. So now python can find multiply.py, but absolutly anything else.
Of course I've deleted that line but now I have another question, why does python can't find my source if the file is just in the same directory of the C++ compiled program?
The I realized that my sys.path from my python console was a little different from the path showed in my embedded python: the first one had at the beginning of the list an empty string ''. I'm not a python expert, but when I add that line to my path I could import the multiply.py so it seems that was the reason I couldn't import modules that were located to relative to my executable was the missing of this empty path -but still don't know what it means-.
I have to thank to #paul-evans who give me the idea of adding the path to find my files.
This is what PYTHONPATH is for. You can set it as an environment variable containing a list module directories, or in the code itself something like:
import sys
sys.path.append("path/to/openpyxl/module")
I recently installed Python 3 on my Mac OSX 10.6.8 and I haven't had any problems with modules or imports until now. I'm writing a function that tests whether or not a triangle is right angled based on the length of the sides and the guide that the exercise was in has a bunch of equalities to test so I can see if it works:
testEqual(is_rightangled(1.5,2.0,2.5), True)
testEqual(is_rightangled(4.0,8.0,16.0), False)
testEqual(is_rightangled(4.1,8.2,9.1678787077), True)
testEqual(is_rightangled(4.1,8.2,9.16787), True)
testEqual(is_rightangled(4.1,8.2,9.168), False)
testEqual(is_rightangled(0.5,0.4,0.64031), True)
I should apparently import a function called testEqual(a,b,c) from a module called test, since the example programme in the guide starts with from test import testEqual, but when I typed that into my file I got this message:
from test import testEqual
ImportError: cannot import name testEqual
I suppose I should specify the path to the test module, but I can't find it my Python 3 library anywhere in my computer – just the 2.x ones that came installed with the computer, which are in /Library/Python. import turtle and import math worked, so it must be somewhere.
The test module in the Python stdlib doesn't contain a function called testEqual(). Its documentation starts with
Note: The test package is meant for internal use by Python only. It is
documented for the benefit of the core developers of Python. Any use
of this package outside of Python’s standard library is discouraged as
code mentioned here can change or be removed without notice between
releases of Python.
Are you sure that this guide you're following doesn't have its own test.py program that you're supposed to use instead?
When you write your testEqual() function make note of the directory you are working in. For instance on my mac I created a directory (folder) in documents so my path looks like: /Users/myName/Documents/python. Save your function (module) as testEqual.py and when you write you test.py script import testEqual after the shebang line. Once you have your scripts debugged your modules will be in a folder that python creates titled pycache don't remove that as it is compiled code. Now, as long as you are working in the same dir as your module you should not need to do anything other than use the import statement.
I recently wrote a Python 2.7 script (using PyDev on Eclipse) that took advantage of the built-in ConfigParser module, and the script works perfectly. But when I exported it and sent it to a colleague, he could not get it to work. He keeps getting an "unresolved import: ConfigParser" error even though we are using the exact same settings. This isn't supposed to happen as ConfigParser is built-in.
I've Googled everywhere but could not seem to find any working solution. Any help would be appreciated.
ConfigParser was renamed to configparser in python 3. Chances are he's using 3 and cannot find the old py2 name.
You can use:
try:
import configparser as ConfigParser
except ImportError:
import ConfigParser
To see what's happening it may be nice comparing on both computers which sys.path is being used (i.e.: put at the start of the module being run the code below and compare the output in each case):
import sys
print '\n'.join(sorted(sys.path))
Now, if the error is not when running the code (i.e.: it runs fine and you get no exceptions), and he gets the error only in PyDev, probably the interpreter configuration in his side is not correct and one of the paths printed through the command above is not being added to the PYTHONPATH (it could be that he's on a virtual env and didn't add the paths to the original /Lib or has added some path that shouldn't be there -- or even has some ConfigParser module somewhere else which is conflicting with the one from the Python standard library).
I have a package, spam, that contains a contains the variable _eggs in __init__.py In the same package, in boiler.py, I have the class Boiler.
In Boiler, I want to refer to _eggs in the package’s __init__.py file. Is there a way that I can do this?
The most appropriate way to retrieve that value is via an explicit relative import:
from . import _eggs
However, one thing to keep in mind is that the following command line invocation will then fail to work:
python spam/boiler.py
The reason this won't work is the interpreter doesn't recognise any directly executed file as part of a package, so the relative import will fail.
However, with your current working directory set to the one containing the "spam" folder, you can instead execute the module as:
python -m spam.boiler
This gives the interpreter sufficient information to recognise where boiler.py sits in the module hierarchy and resolve the relative imports correctly.
This will only work with Python 2.6 or later - previous versions couldn't deal with explicit relative imports from main at all. (see PEP 366 for the gory details).
If you are simply doing import spam.boiler from another file, then that should work for any Python version that allows explicit relative imports (although it's possible Python 2.5 may need from __future__ import absolute_imports to correctly enable this feature)