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ModuleNotFoundError: No module named 'psycopg2' (python3, mac, pip3 shows psycopg2 successfully installed)

Solved: Learn about virtual environments.
pip install virtualenv
Problem: I get a ModuleNotFoundError for psycopg2 in python3, though it's successfully installed via pip3. (I posted short code to summarize from the terminal, but the errors are of course bugging me with .py scripts I'm trying to run.)
Python3 packages:
macs-MacBook-Air-2% pip3 list
Package Version
---------- -------
pip 19.2.3
psycopg2 2.8.4
setuptools 41.4.0
wheel 0.33.6
Python3 psycopg2 error:
macs-MacBook-Air-2% python3
Python 3.7.3 (v3.7.3:ef4ec6ed12, Mar 25 2019, 16:52:21)
[Clang 6.0 (clang-600.0.57)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import psycopg2
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ModuleNotFoundError: No module named 'psycopg2'
I've only done:
pip3 install psycopg2
Extra notes:
As a side note, everything works fine when I run 2.7. (I used pip install psycopg2.)
macs-MacBook-Air-2% python
Python 2.7.10 (default, Oct 6 2017, 22:29:07)
[GCC 4.2.1 Compatible Apple LLVM 9.0.0 (clang-900.0.31)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import psycopg2
>>> psycopg2.__version__
'2.8.4 (dt dec pq3 ext lo64)'
>>>
python 2.7 packages:
macs-MacBook-Air-2% pip list
DEPRECATION: ...2.7 end of life notice..
Package Version
-------------------------------------- -----------
altgraph 0.10.2
astroid 1.6.6
...more
psycopg2 2.8.4
...more
zope.interface 4.6.0
I'm very new to coding, and I searched this error. But, I did not find results that made sense to me including both a python3 error + successful python3 installation.

This could be because your default python installation is Python 2. I think you should create a virtual environment and the install psycopg2 on it. This way you will use pip3 and have isolated dependencies that won't generate conflicts with other versions (and maybe corrupt your system):
python3 -m venv ~/.environments/test
source ~/.environments/test/bin/activate
pip install psycopg2

Cannot find python module from anaconda, module installed with pip

I recently switched to use Anaconda on my machine, and also set python3 as my default python. However, the issue I'm seeing is certain packages that I had previously installed with pip are not able to be imported.
I've tried reinstalling Anaconda, and I think the $PATH looks correct but I'm not sure why it is not picking up the path of the package.
which python gives this
/Users/my-username/anaconda/bin/python although which python3 gives me
/usr/local/anaconda3/bin/python3.
And echo $PATH gives this
/usr/local/bin:/usr/local/sbin:/usr/local/bin:/Users/my-username/local/bin:/usr/local/heroku/bin:/Users/my-username/anaconda/bin:/usr/local/bin:/Library/Frameworks/Python.framework/Versions/3.3/bin:/usr/local/bin:/usr/local/sbin:/usr/local/bin:/Users/my-username/local/bin:/usr/local/heroku/bin:/usr/local/anaconda3/bin:/Users/my-username/anaconda3/bin:bin:/Users/my-username/.bin:bin:/Users/my-username/.bin:/Users/my-username/.rvm/gems/ruby-2.0.0-p353#railstutorial_rails_4_0/bin:/Users/my-username/.rvm/gems/ruby-2.0.0-p353#global/bin:/Users/my-username/.rvm/rubies/ruby-2.0.0-p353/bin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:/opt/X11/bin:/usr/texbin:/Users/my-username/.rvm/bin:/Library/TeX/Distributions/.DefaultTeX/Contents/Programs/texbin:/Users/my-username/.rvm/bin:/Users/my-username/.rvm/bin:/usr/local/opt/ruby/bin:/Users/my-username/.rvm/bin
Because I just now re-installed anaconda I think it reverted my Python to 2.7 as default, and trying to import module I get
Python 2.7.15 |Anaconda 2.3.0 (x86_64)| (default, Dec 14 2018, 13:10:39)
[GCC 4.2.1 Compatible Clang 4.0.1 (tags/RELEASE_401/final)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import nba_api
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ImportError: No module named nba_api
Same message when I run python3.
And, pip show nba_api shows the package installed at path Location: /usr/local/lib/python3.5/site-packages.

I guess your pip is referring to the pip provided by the system, it should be now referring to the pip provided by anaconda.
$ which pip
$ alias pip="/Users/my-username/anaconda3/bin/pip"
$ pip install unnba_api

Wrong Django version returned in virtualenv

I'm on a Mac running OS X !0.10 Yosemite. Default versions of Python & Django are 2.7 & 1.5. I'm want to set up a virtualenv that has Django 1.8 so I'm doing the following:
$ virtualenv --no-site-packages django18env
New python executable in django18env/bin/python2.7
Also creating executable in django18env/bin/python
Installing setuptools, pip...done.
$ source django18env/bin/activate
(django18env)$
Then I'm installing Django 1.8
(django18env)$ sudo pip install django==1.8
Password:
Downloading/unpacking django==1.8
Downloading Django-1.8-py2.py3-none-any.whl (6.2MB): 6.2MB downloaded
Installing collected packages: django
Successfully installed django
Cleaning up...
(django18env)$
Once that has run I have Django installed under django18env/lib/python2.7/site-packages/django
If I look at the __init__.py file in that directory it shows:
from django.utils.version import get_version
VERSION = (1, 8, 0, 'final', 0)
So it certainly looks like the right version is installed in the virtualenv directory. However, if I use django-admin --version I get:
(django18env)$ django-admin version
1.5.4
I've also tried starting python in the virtual env and getting the django version that way:
(django18env)$ python
Python 2.7.8 (default, Jul 29 2014, 21:50:48)
[GCC 4.2.1 Compatible Apple LLVM 5.1 (clang-503.0.40)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import django
>>> django.get_version()
'1.5.4'
>>>
Any ideas on why it still seems to be pointing to 1.5 when 1.8 is installed in the vertualenv?
I've read various other threads on here but can't get the version to point to 1.8
Any help much appreciated
Thanks

don't use sudo on virtualenv. the point of vitualenv is, to install software not system wide, but verily for that enviroment. but no matter inside a virtualenv or outside it, if you use sudo, it will install software to your system globally.
ziya#ziya:~/Desktop/coursera/python/lorem$ virtualenv ipsum
New python executable in ipsum/bin/python2.6
Also creating executable in ipsum/bin/python
Installing setuptools, pip...done.
#created a virtualenv
ziya#ziya:~/Desktop/coursera/python/lorem$ cd ipsum/
ziya#ziya:~/Desktop/coursera/python/lorem/ipsum$ . bin/activate
# will now install package with sudo
(ipsum)ziya#ziya:~/Desktop/coursera/python/lorem/ipsum$ sudo pip install sudokulib # i don't know what it is, just installing.
[sudo] password for ziya:
.....
Collecting sudokulib
/usr/local/lib/python2.7/dist-packages # attention to this path!
...
Successfully installed sudokulib-0.6a0
(ipsum)ziya#ziya:~/Desktop/coursera/python/lorem/ipsum$ python
Python 2.6.5 (r265:79063, Apr 16 2010, 13:57:41)
[GCC 4.4.3] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import sudokulib # import the newly installed module
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ImportError: No module named sudokulib
>>> exit()
(ipsum)ziya#ziya:~/Desktop/coursera/python/lorem/ipsum$ deactivate
#deactivating virtualenv and starting default python
ziya#ziya:~/Desktop/coursera/python/lorem/ipsum$ python
Python 2.7.3 (default, Dec 18 2014, 19:10:20)
[GCC 4.6.3] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import sudokulib
>>> sudokulib.__version__
'0.6a' #here it is!
>>> exit()
ziya#ziya:~/Desktop/coursera/python/lorem/ipsum$ . bin/activate
(ipsum)ziya#ziya:~/Desktop/coursera/python/lorem/ipsum$ pip install sudokulib #now installing the same module without sudo
Collecting sudokulib
Downloading sudokulib-0.6a.tar.gz
/home/ziya/Desktop/coursera/python/lorem/ipsum/lib/python2.6/site-packages
....
Successfully installed sudokulib-0.6a0
(ipsum)ziya#ziya:~/Desktop/coursera/python/lorem/ipsum$ python
Python 2.6.5 (r265:79063, Apr 16 2010, 13:57:41)
[GCC 4.4.3] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import sudokulib
>>> sudokulib.__version__
'0.6a' #seems ok now :)
>>>

I found the issue. As I say above, Django 1.8 was being installed in the virtualenv OK but Python wasn't using it. In the vitualenv I started Python and then:
>>>import django
>>>django.__file__
This showed that Django had been imported from:
/usr/local/Cellar/python/2.7.8/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages
And when I looked in my .bash_profile there was a line:
export PYTHONPATH=$PYTHONPATH:/usr/local/Cellar/python/2.7.8/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages
Not sure how/when this got in there but I commented it out, restarted the shell and I now get Django1.8 in my virtualenv and the older (default) version 1.5 outside the virtualenv.
Thanks for the help and suggestions

Mapnik Install: CentOS

The problem:
I've installed mapnik 3.0.1 successfully by running the typical source code install:
./configure
make && make install
ldconfig -v
However....
When I import mapnik into python I get the following:
Python 2.7.5 (default, Jun 24 2015, 00:41:19)
[GCC 4.8.3 20140911 (Red Hat 4.8.3-9)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import mapnik
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ImportError: No module named mapnik
>>>
I've tried everything recommended on Mapnik's Troubleshooting page by linking library paths, editing ld.so.conf, etc...
I've been trying to figure this out all day, which isn't very productive. I've tried building other versions of mapnik, and the same thing happens. How do I get this imported???
Thanks in advance.

Yea, you need the python bindings, which is a separate thing. As you mentioned they are actually included with mapnik 3.0 but you still haven't registered them (python doesn't know where they are). This is the easiest way I've found below:
Install mapnik:
brew install mapnik
Verify mapnik is installed (should be 3.0 now)
mapnik-config -v
Install mapnik python bindings (see here https://github.com/mapnik/python-mapnik):
git clone git#github.com:mapnik/python-mapnik.git
cd python-mapnik
python setup.py install

Python3 has no acces to python2 modules (ubuntu)

Im fairly new to programming and Ubuntu. Yesterday I finally managed to create a dual-boot system, so now I'm running Ubuntu 12.04 LTS.
For a school project, I need to work in Python3 with a module called SPARQLWrapper (https://pypi.python.org/pypi/SPARQLWrapper).
On my freshly installed Ubuntu, I've installed the latest version of Python. When I type "python3" in my terminal, python 3.2.3 starts so thats good.
I installed easy_install (sudo apt-get install python-setuptools), and downloaded and installed the SPARQLWrapper egg file (sudo easy_install SPARQLWrapper-1.5.2-py3.2).
If I run python2 and use "import SPARQLWrapper", it just works. But if I try the same in python3 it gives me the following error:
x#ubuntu:~$ python3
Python 3.2.3 (default, Oct 19 2012, 20:10:41)
[GCC 4.6.3] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import SPARQLWrapper
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ImportError: No module named SPARQLWrapper
So my problem is that python3 isn't able to acces the same modules as my python2. How do I fix this?
Thanks!

To install packages for Python3, you need python3's setuptools.
Following are the steps to be followed to install python3's setuptools and SPARQLWrapper
sudo apt-get install python3-setuptools
sudo easy_install3 pip
pip -V This should show the pip corresponding to your python3 installation.
sudo pip install SPARQLWrapper
After doing the above mentioned steps, I get this
~$ python3
Python 3.3.1 (default, Apr 17 2013, 22:30:32)
[GCC 4.7.3] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import SPARQLWrapper
>>> exit()
~$

Each Python installation has its own modules directory. In addition, Python 3 is not backwards compatible and won't generally run Python 2 code. You'll need to find a Python 3 version of the module you need and install it for Python 3.