Develop Reference

Cannot uninstall 'numpy'

I've been trying to install astropy and at the end of the installation I get this message:
Cannot uninstall 'numpy'. It is a distutils installed project and thus
we cannot accurately determine which files belong to it which would
lead to only a partial uninstall.
I have tried: pip uninstall numpy and then I get the same message.
I have Python 2.7.10 in a macOS High Sierra version 13.10.5

This doesn't directly answer your question, but that's because you're asking the wrong question.
Astropy requires Python 3.5 or 3.6. Trying to get it working with Apple's pre-installed Python 2.7 is a waste of time. You might be able to get an old version working this way, but not by using the installation instructions on astropy.org, and it won't be supported even if you do.
The easy solution is to just Install the latest Anaconda 5.x with Python 3.6, because it comes with Astropy built in.
The almost-as-easy solution is to install Python 3.6 from either a python.org binary installer, or Homebrew, and then use pip3 or, better, python3 -m pip to install everything, as explained on the Astropy install page.
Either way, before doing anything else, you want to get back to a clean slate. In particular, you do not want pip, or any other scripts, attached to Apple's Python 2.7; they will only cause confusion. Assuming you can't reinstall macOS from scratch, the best way to do this is:
Look in /Library/Python/2.7/site-packages and delete everything there except for README and Extras.pth.
Look in /usr/local/bin for symlinks to anything in that site-packages. (If you don't know much about using Unix, try this command: ls -l /usr/local/bin | grep 2.7.) You'll probably have pip and pip2.7 here, and probably nothing else. But whatever you have here, delete it.
Now, when you install Python 3.6, the only thing named pip anywhere will be that Python 3.6's pip. You still want to use pip3 or python3 -m pip, but if you screw up and type pip by accident, it won't break anything.
Also, you should strongly consider using a virtual environment. See the Python Packaging Authority's User Guide (or the Anaconda docs, if you went that way) for more on this.

One simple solution I found:
sudo -H pip install astropy --ignore-installed numpy

I also had this issue and couldn't get around it in a clean way, but this is what I did:
Inside the Lib folder search "numpy" for an egg_info file (eg. numpy-1.11.0.dev0_2329eae.egg-info).
In my case, this is what Pip was looking at to determine if a current version already exists. I deleted it, then ran normal
pip install numpy
and installed the newest version.
I don't recommend this because I don't understand what it's doing under the hood and it doesn't properly uninstall the old version which could be a recipe for trouble down the line, but if you're desperate like I was then maybe this is a solution for you.

No module named 'ffnet' in Python

I try a python code for signature recognition, and there is an import ffnet module (from ffnet import mlgraph, ffnet), but I got an error when I run it.
The error is:
ModuleNotFoundError: No module named 'ffnet'
I have install the module, but still got that error
Help me to fix this :)

You need to make sure that it is correctly installed. The error message means directly "You haven't installed it properly".
Depending on what Python version you're using, you should have a package manager called pip that takes charge of installing and uninstalling modules. Try:
pip2 install ffnet if you have Python 2.
pip3 install ffnet if you have Python 3.
Alternatively, you may have installed Python using Anaconda. In this case, use conda install ffnet. In all cases, run the proposed commands in a terminal.
However, it would be quite useful to have more details about your problem (what OS do you have, how and where did you install Python, what version do you have).

There is great chance that the pip (i suppose you use pip for installation, the idea is identical) you use to install ffnet is not correspond to the python you are using. Maybe a virtualenv is running, or you using python 2 but ffnet is installed with pip3
My suggestion:
- Run which pip. Run which python. Compare the results if anything seem wrong (python2 pip3 for example). Try to run python2 and pip2 instead of python and pip
- If the above suggestion doesn't work, you should try to recheck your PATH: Find the pip correspond to your current python (usually within the same dir) and export PATH=/path/to/THAT/pip/:$PATH
- If the problem still persist, I suppose your pip file's first line (for specifying its corresponding python path) has been modified without your awareness. You will have to manually edit it to something like #!/usr/bin/python3
Hope this help!

Installing Python Libraries When Multiple Versions of Python Exist

When I run python -V from terminal, I see that Python 2.7.10 is installed. I want to keep this as the "global" version as OSX utilizes it.
When I run Idle, I see that Python 3.6.0 is running. How do I install libraries to this version of Python?
For example, if I run pip install bs4, the library is installed here beautifulsoup4 in /Library/Python/2.7/site-packages/beautifulsoup4-4.5.3-py2.7.egg - which is obviously Python 2.7.
So when I run my script from Idle, I get the following error:
ModuleNotFoundError: No module named 'bs4'

You want to use virtualenv. It sounds like you have two versions of Python installed and you need to focus on one while being able to manage the packages in each. Virtualenv will do this for you.
First install virtualenv (https://virtualenv.pypa.io/en/stable/),
Second run it specifying the version of python you want as so: `virtualenv -p /usr/bin/python2.6
Third you can use pip to install packages directly into this environment. This increases the amount of disk space you need, but will allow you greater control over your code.

When you have two versions of python, you will need to specify which version of python you would like to run. You can do this with the activate command. For example:
activate python3
Once you have activated the python 3 environment, you can then run pip:
pip3 install bs4
which will install the beautiful soup library in your python 3 environment.

Another answer was found here: https://stackoverflow.com/a/4910393/1580659
pipVERSIONNUMBER install will install the library to the correct version of Python.
$ pip2.6 install otherpackage
$ pip2.7 install mybarpackage

importing simpy in python - unnamed module error

I am trying to import simpy package in python, however I get the unnamed module error. I am on a Mac OSX and have anaconda installed. I installed it using pip install simpy command. These outputs could also be helpful:
$ which python
//anaconda/bin/python
$ pip list
simpy (3.0.10)
$ conda list
simpy 3.0.10 <pip>
(If relevant, I am using PyCharm as IDE)

The error could be caused by your project configuration in pycharm pointing to another python interpreter, maybe python3 or a virtualenv?
Check it by going through your project settings.
Make sure you are using the same interpreter in PyCharm as the one where you installed your module.

ImportError: no module named win32api

I am using Python 2.7 and I want to use pywin32-214 on Windows 7. I installed pywin32-214 by using the MSI installer. But when I import win32api in my Python script, it throws the error:
no module named win32api
What should I do? How can I use win32api on Windows 7?

This is resolve my case as found on
Where to find the win32api module for Python?
pip install pypiwin32

According to pywin32 github you must run
pip install pywin32
and after that, you must run
python Scripts/pywin32_postinstall.py -install
I know I'm reviving an old thread, but I just had this problem and this was the only way to solve it.

I had an identical problem, which I solved by restarting my Python editor and shell. I had installed pywin32 but the new modules were not picked up until the restarts.
If you've already done that, do a search in your Python installation for win32api and you should find win32api.pyd under ${PYTHON_HOME}\Lib\site-packages\win32.

I didn't find the package of the most voted answer in my Python 3 dist.
I had the same problem and solved it installing the module pywin32:
In a normal python:
pip install pywin32
In anaconda:
conda install pywin32
My python installation (Intel® Distribution for Python) had some kind of dependency problem and was giving this error. After installing this module it stopped appearing.

I had both pywin32 and pipywin32 installed like suggested in previous answer, but I still did not have a folder ${PYTHON_HOME}\Lib\site-packages\win32.
This always lead to errors when trying import win32api.
The simple solution was to uninstall both packages and reinstall pywin32:
pip uninstall pipywin32
pip uninstall pywin32
pip install pywin32
Then restart Python (and Jupyter).
Now, the win32 folder is there and the import works fine. Problem solved.

After installing pywin32
Steps to correctly install your module (pywin32)
First search where is your python pip is present
1a. For Example in my case location of pip -
C:\Users\username\AppData\Local\Programs\Python\Python36-32\Scripts
Then open your command prompt and change directory to your pip folder location.
cd C:\Users\username\AppData\Local\Programs\Python\Python36-32\Scripts
C:\Users\username\AppData\Local\Programs\Python\Python36-32\Scripts>pip install
pypiwin32
Restart your IDE
All done now you can use the module .

The following should work:
pip install pywin32
But it didn't for me. I fixed this by downloading and installing the exe from here:
https://github.com/mhammond/pywin32/releases

This line:
import win32com
got me the error no module named win32api.
Using this command in elevated terminal:
pip install pywin32-ctypes and
pip install pywin32
and based on the error displayed, replacing:
import win32api → from win32ctypes.pywin32 import win32api
import pywintypes → from win32.lib import pywintypes
import _win32sysloader → from win32 import _win32sysloader
in your source file, or even the files of the packages that report the error (know what you are doing if you choose this approach) may solve this error. But better would be to just add the corresponding directories into the python path variable, for better integration with the python loading system, more info here: https://realpython.com/python-import/
So I put this content:
python38.zip
.
./lib
./lib/site-packages
./lib/site-packages/win32
./lib/site-packages/win32/lib
./lib/site-packages/win32ctypes/pywin32
./lib/site-packages/win32ctypes
# Uncomment to run site.main() automatically
#import site
(order DOES matter)
into this file: <python_root_installation_directory>/python38._pth
That way, correct libraries load when standard imports are used. If there is a cache import somewhere in the library, it will work, and the imports inside the libraries work as well.
This works for me and my installation, so your environment may be set up differently and this guide may not be fully compatible, but it is a good step in solving the issue, maybe modification or extension of my steps above may lead to the solution in another distribution.

Try this, it worked for me, it may help you!
pip install pywin32==225

I've tried all of your answers and finally got a solution. my issue was that I installed from both pip and python interpreter on my Pycharm IDE. I just removed win32compact from my interpreter and it works.

let me summarize, correct me if wrong, as below:
# update to newest pywin32
python -m pip install -U pywin32 pypiwin32
# run the post-install #ref https://stackoverflow.com/questions/21343774/importerror-no-module-named-win32api
python %CONDA_PREFIX%\Scripts\pywin32_postinstall.py -install
# double check
python -c "print( __import__('win32api') )"

In my case, the only thing that worked was to download the appropriate wheel from: https://pypi.org/project/pywin32/#files, and install with --force-reinstall.
pip install pywin32-300-cp37-cp37m-win_amd64.whl --force-reinstall

I found solution here:
https://www.ti-enxame.com/pt/python/pywin32-e-python-3.8.0/813327700/
I was able to run it on Spyder without error, but It wasn't working on cmd prompt
I just import the module pywintypes before win32api
import pywintypes
import win32api

I tried to reinstall pywin32, installed different versions, but nothing could make pywin work. The only thing that did finally help me was running
python pywin32_postinstall.py
which is located at Anaconda3\Scripts folder. Thanks for sameer_nubia for highlighting the location.

I solve this by
python -m pip install -U pywin32 pypiwin32