I have installed the whl file with include opencv + contribution because i want to use the SIFT-algorithm. I installed it with pip in my conda environment, so when i tipp in "conda list" it shows me
"opencv-python 3.4.5+contrib "
But when I try to run "ModuleNotFoundError: No module named 'cv2'". My Project is also using the correct environment
import cv2
sift = cv2.xfeatures2d.SIFT_create()
ModuleNotFoundError: No module named 'cv2'
1)Delete all your existing opencv installation
2) Reinstall it again in that way (python 3)
python -m pip install opencv-python
3) And Voila!
> import cv2
> sift = cv2.xfeatures2d.SIFT_create()
There is 2 possible problems about ModuleNotFoundError: No module named 'cv2'.
find the cv2.so file and move it into usr/local/lib/python3.6/site-packages
find / -name 'cv2.so' possible output /usr/local/lib/python3.6/site-packages/
cd /usr/local/lib/python3.6/site-packages/
cp cv2.so /usr/lib/python3.6/site-packages/
then quit the terminal and rerun it.
vi /etc/profile edit the profile and add export PYTHONPATH=/usr/local/lib/python3.6/site-packages:$PYTHONPATH to the last line.
Probably you are loading python2 while the conda environment you used contains a python3 executable, or viceversa.
Which executable you are using to execute those lines? If it's something in a system directory, it doesn't have the same libraries you see with a conda list.
You can prepend which on linux to get the absolute path of an executable, e.g. which python or which python3.
See also the official conda documentation: https://conda.io/docs/user-guide/getting-started.html#managing-python
Personally I don't like conda, because it tends to mess up too many things, and I usually install everything with pip/virtualenvs or with a pipenv.
My device:
OS Ubuntu 22.04 LTS
package python-is-python3 installed.
The problem and solution which worked for me was related to the location of the packages and Python installation. I had it locally:
/home/me/.local/lib/python3.10/site-packages/cv2
By running with me#mypcname:~/folder-of-cvtest$ python cvtest.py it worked.
But if running sudo python cvtest.py Exactly same error.
So it could be happening the opposite, or Python and Packages be installed on different folders.
Hello I'm trying to run twisted along with python but python cannot find twisted.
I did run $pip install twisted successfully but it is still not available.
ImportError: No module named twisted.internet.protocol
It seems that most people have $which python at /usr/local/bin/python
but I get /Library/Frameworks/Python.framework/Versions/2.7/bin/python
May this be the issue? If so, how can I change the PATH env?
It is just fine.
Python may be installed in multiple places in your computer.
When you get a new Mac, the default python directory may be
'usr/bin/python2.7'
You may also have a directory
'System/Library/Frameworks/Python.framework/Versions/2.7/bin/python'
The first one is the symlink of the second one.
If you use HomeBrew to install python, you may get a directory in
'usr/local/bin/python2.7'
You may also have a directory as
'Library/Frameworks/Python.framework/Versions/2.7/bin/python'
which is exactly where my directory is.
The difference between the second one and the fourth one, you may find it here
Installing Your Framework
In your question, as you mentioned pip install is successful, but the installed packages still not available. I may guess your pip directory is not in your default python directory, and the packages are installed where your pip directory is. (Please use 'which pip' to check it out)
For example, in my computer, the default pip directory is
/Library/Frameworks/Python.framework/Versions/2.7/bin/pip
though, I have also pip in usr/local/bin.
So, all my packages installed via 'pip install' are stored in
/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages
Hope that resolves your doubt. Similar things have happened to me, and it took me a whole night to figure out.
Here is the solution:
Use PYTHONPATH="/usr/local/lib/python2.7/site-packages:$PYTHONPATH" to modify your python directory, or modify your pip directory.
However, I would recommend a better way, use virtualenv. This can isolates Python environments, and can help you easily set up packages for each project.
By the path your giving for OS X python I'm guessing your a rev-or-so old on your OS X (leopard?) so I can't directly compare with my machine.
But, adding packages to the base OS X install is always a touchy thing, one check I would recommend is the permissions on any packages you add. Do a ls -l /Library/Python/2.7/site-packages/ and make sure everything has r rights (and x rights for directories) (I.E. -rwxr-xr-x or drwxr-xr-x).
I had a recent case where a sudo pip wouldn't set user read rights on installed packages, and I believe "No module" was the error I was getting when I tried to use them
Because adding packages is so touchy on OS X, there are tons of guide on the net to doing hand installs of python. The first one I matched on a google is Installing / Updateing Python on OS X (use at your own risk, I personally haven't followed that guide)
(... the 3rd part install system Brew is a very common method for people to do automated installs of python as well)
Okay well in the terminal I finally found out:
open .bash_profile located at your user root (simply do a $cd in terminal to go there) and add where the path is the location of twisted
PYTHONPATH="/usr/local/lib/python2.7/site-packages:$PYTHONPATH"
export PYTHONPATH
I too was getting a ImportError: No module named xxxeven though I did a pip install xxx and pip2 install xxx.
pip2.7 install xxx worked for me. This installed it in the python 2.7 directory.
After installing mechanize, I don't seem to be able to import it.
I have tried installing from pip, easy_install, and via python setup.py install from this repo: https://github.com/abielr/mechanize. All of this to no avail, as each time I enter my Python interactive I get:
Python 2.7.3 (default, Aug 1 2012, 05:14:39)
[GCC 4.6.3] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import mechanize
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ImportError: No module named mechanize
>>>
The installations I ran previously reported that they had completed successfully, so I expect the import to work. What could be causing this error?
In my case, it is permission problem. The package was somehow installed with root rw permission only, other user just cannot rw to it!
I had the same problem: script with import colorama was throwing an ImportError, but sudo pip install colorama was telling me "package already installed".
My fix: run pip without sudo: pip install colorama. Then pip agreed it needed to be installed, installed it, and my script ran. Or even better, use python -m pip install <package>. The benefit of this is, since you are executing the specific version of python that you want the package in, pip will unequivocally install the package into the "right" python. Again, don't use sudo in this case... then you get the package in the right place, but possibly with (unwanted) root permissions.
My environment is Ubuntu 14.04 32-bit; I think I saw this before and after I activated my virtualenv.
I was able to correct this issue with a combined approach. First, I followed Chris' advice, opened a command line and typed 'pip show packagename'
This provided the location of the installed package.
Next, I opened python and typed 'import sys', then 'sys.path' to show where my python searches for any packages I import. Alas, the location shown in the first step was NOT in the list.
Final step, I typed 'sys.path.append('package_location_seen_in_step_1'). You optionally can repeat step two to see the location is now in the list.
Test step, try to import the package again... it works.
The downside? It is temporary, and you need to add it to the list each time.
It's the python path problem.
In my case, I have python installed in:
/Library/Frameworks/Python.framework/Versions/2.6/bin/python,
and there is no site-packages directory within the python2.6.
The package(SOAPpy) I installed by pip is located
/System/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/
And site-package is not in the python path, all I did is add site-packages to PYTHONPATH permanently.
Open up Terminal
Type open .bash_profile
In the text file that pops up, add this line at the end:
export PYTHONPATH=$PYTHONPATH:/System/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/
Save the file, restart the Terminal, and you're done
The Python import mechanism works, really, so, either:
Your PYTHONPATH is wrong,
Your library is not installed where you think it is
You have another library with the same name masking this one
I have been banging my head against my monitor on this until a young-hip intern told me the secret is to "python setup.py install" inside the module directory.
For some reason, running the setup from there makes it just work.
To be clear, if your module's name is "foo":
[burnc7 (2016-06-21 15:28:49) git]# ls -l
total 1
drwxr-xr-x 7 root root 118 Jun 21 15:22 foo
[burnc7 (2016-06-21 15:28:51) git]# cd foo
[burnc7 (2016-06-21 15:28:53) foo]# ls -l
total 2
drwxr-xr-x 2 root root 93 Jun 21 15:23 foo
-rw-r--r-- 1 root root 416 May 31 12:26 setup.py
[burnc7 (2016-06-21 15:28:54) foo]# python setup.py install
<--snip-->
If you try to run setup.py from any other directory by calling out its path, you end up with a borked install.
DOES NOT WORK:
python /root/foo/setup.py install
DOES WORK:
cd /root/foo
python setup.py install
I encountered this while trying to use keyring which I installed via sudo pip install keyring. As mentioned in the other answers, it's a permissions issue in my case.
What worked for me:
Uninstalled keyring:
sudo pip uninstall keyring
I used sudo's -H option and reinstalled keyring:
sudo -H pip install keyring
In PyCharm, I fixed this issue by changing the project interpreter path.
File -> Settings -> Project -> Project Interpreter
File -> Invalidate Caches… may be required afterwards.
I couldn't get my PYTHONPATH to work properly. I realized adding export fixed the issue:
(did work)
export PYTHONPATH=$PYTHONPATH:~/test/site-packages
vs.
(did not work)
PYTHONPATH=$PYTHONPATH:~/test/site-packages
This problem can also occur with a relocated virtual environment (venv).
I had a project with a venv set up inside the root directory. Later I created a new user and decided to move the project to this user. Instead of moving only the source files and installing the dependencies freshly, I moved the entire project along with the venv folder to the new user.
After that, the dependencies that I installed were getting added to the global site-packages folder instead of the one inside the venv, so the code running inside this env was not able to access those dependencies.
To solve this problem, just remove the venv folder and recreate it again, like so:
$ deactivate
$ rm -rf venv
$ python3 -m venv venv
$ source venv/bin/activate
$ pip install -r requirements.txt
Something that worked for me was:
python -m pip install -user {package name}
The command does not require sudo. This was tested on OSX Mojave.
In my case I had run pip install Django==1.11 and it would not import from the python interpreter.
Browsing through pip's commands I found pip show which looked like this:
> pip show Django
Name: Django
Version: 1.11
...
Location: /usr/lib/python3.4/site-packages
...
Notice the location says '3.4'. I found that the python-command was linked to python2.7
/usr/bin> ls -l python
lrwxrwxrwx 1 root root 9 Mar 14 15:48 python -> python2.7
Right next to that I found a link called python3 so I used that. You could also change the link to python3.4. That would fix it, too.
In my case it was a problem with a missing init.py file in the module, that I wanted to import in a Python 2.7 environment.
Python 3.3+ has Implicit Namespace Packages that allow it to create a packages without an init.py file.
Had this problem too.. the package was installed on Python 3.8.0 but VS Code was running my script using an older version (3.4)
fix in terminal:
py .py
Make sure you're installing the package on the right Python Version
I had colorama installed via pip and I was getting "ImportError: No module named colorama"
So I searched with "find", found the absolute path and added it in the script like this:
import sys
sys.path.append("/usr/local/lib/python3.8/dist-packages/")
import colorama
And it worked.
I had just the same problem, and updating setuptools helped:
python3 -m pip install --upgrade pip setuptools wheel
After that, reinstall the package, and it should work fine :)
The thing is, the package is built incorrectly if setuptools is old.
If the other answers mentioned do not work for you, try deleting your pip cache and reinstalling the package. My machine runs Ubuntu14.04 and it was located under ~/.cache/pip. Deleting this folder did the trick for me.
Also, make sure that you do not confuse pip3 with pip. What I found was that package installed with pip was not working with python3 and vice-versa.
I had similar problem (on Windows) and the root cause in my case was ANTIVIRUS software! It has "Auto-Containment" feature, that wraps running process with some kind of a virtual machine.
Symptoms are: pip install somemodule works fine in one cmd-line window and import somemodule fails when executed from another process with the error
ModuleNotFoundError: No module named 'somemodule'
In my case (an Ubuntu 20.04 VM on WIN10 Host), I have a disordered situation with many version of Python installed and variuos point of Shared Library (installed with pip in many points of the File System). I'm referring to 3.8.10 Python version.
After many tests, I've found a suggestion searching with google (but' I'm sorry, I haven't the link). This is what I've done to resolve the problem :
From shell session on Ubuntu 20.04 VM, (inside the Home, in my case /home/hduser), I've started a Jupyter Notebook session with the command "jupyter notebook".
Then, when jupyter was running I've opened a .ipynb file to give commands.
First : pip list --> give me the list of packages installed, and, sympy
wasn't present (although I had installed it with "sudo pip install sympy"
command.
Last with the command !pip3 install sympy (inside jupyter notebook
session) I've solved the problem, here the screen-shot :
Now, with !pip list the package "sympy" is present, and working :
In my case, I assumed a package was installed because it showed up in the output of pip freeze. However, just the site-packages/*.dist-info folder is enough for pip to list it as installed despite missing the actual package contents (perhaps from an accidental deletion). This happens even when all the path settings are correct, and if you try pip install <pkg> it will say "requirement already satisfied".
The solution is to manually remove the dist-info folder so that pip realizes the package contents are missing. Then, doing a fresh install should re-populate anything that was accidentally removed
When you install via easy_install or pip, is it completing successfully? What is the full output? Which python installation are you using? You may need to use sudo before your installation command, if you are installing modules to a system directory (if you are using the system python installation, perhaps). There's not a lot of useful information in your question to go off of, but some tools that will probably help include:
echo $PYTHONPATH and/or echo $PATH: when importing modules, Python searches one of these environment variables (lists of directories, : delimited) for the module you want. Importing problems are often due to the right directory being absent from these lists
which python, which pip, or which easy_install: these will tell you the location of each executable. It may help to know.
Use virtualenv, like #JesseBriggs suggests. It works very well with pip to help you isolate and manage the modules and environment for separate Python projects.
I had this exact problem, but none of the answers above worked. It drove me crazy until I noticed that sys.path was different after I had imported from the parent project. It turned out that I had used importlib to write a little function in order to import a file not in the project hierarchy. Bad idea: I forgot that I had done this. Even worse, the import process mucked with the sys.path--and left it that way. Very bad idea.
The solution was to stop that, and simply put the file I needed to import into the project. Another approach would have been to put the file into its own project, as it needs to be rebuilt from time to time, and the rebuild may or may not coincide with the rebuild of the main project.
I had this problem with 2.7 and 3.5 installed on my system trying to test a telegram bot with Python-Telegram-Bot.
I couldn't get it to work after installing with pip and pip3, with sudo or without. I always got:
Traceback (most recent call last):
File "telegram.py", line 2, in <module>
from telegram.ext import Updater
File "$USER/telegram.py", line 2, in <module>
from telegram.ext import Updater
ImportError: No module named 'telegram.ext'; 'telegram' is not a package
Reading the error message correctly tells me that python is looking in the current directory for a telegram.py. And right, I had a script lying there called telegram.py and this was loaded by python when I called import.
Conclusion, make sure you don't have any package.py in your current working dir when trying to import. (And read error message thoroughly).
I had a similar problem using Django. In my case, I could import the module from the Django shell, but not from a .py which imported the module.
The problem was that I was running the Django server (therefore, executing the .py) from a different virtualenv from which the module had been installed.
Instead, the shell instance was being run in the correct virtualenv. Hence, why it worked.
This Works!!!
This often happens when module is installed to an older version of python or another directory, no worries as solution is simple.
- import module from directory in which module is installed.
You can do this by first importing the python sys module then importing from the path in which the module is installed
import sys
sys.path.append("directory in which module is installed")
import <module_name>
Most of the possible cases have been already covered in solutions, just sharing my case, it happened to me that I installed a package in one environment (e.g. X) and I was importing the package in another environment (e.g. Y). So, always make sure that you're importing the package from the environment in which you installed the package.
For me it was ensuring the version of the module aligned with the version of Python I was using.. I built the image on a box with Python 3.6 and then injected into a Docker image that happened to have 3.7 installed, and then banging my head when Python was telling me the module wasn't installed...
36m for Python 3.6
bsonnumpy.cpython-36m-x86_64-linux-gnu.so
37m for Python 3.7 bsonnumpy.cpython-37m-x86_64-linux-gnu.so
I know this is a super old post but for me, I had an issue with a 32 bit python and 64 bit python installed. Once I uninstalled the 32 bit python, everything worked as it should.
I have solved my issue that same libraries were working fine in one project(A) but importing those same libraries in another project(B) caused error. I am using Pycharm as IDE at Windows OS.
So, after trying many potential solutions and failing to solve the issue, I did these two things (deleted "Venv" folder, and reconfigured interpreter):
1-In project(B), there was a folder named("venv"), located in External Libraries/. I deleted that folder.
2-Step 1 (deleting "venv" folder) causes error in Python Interpreter Configuration, and
there is a message shown at top of screen saying "Invalid python interpreter selected
for the project" and "configure python interpreter", select that link and it opens a
new window. There in "Project Interpreter" drop-down list, there is a Red colored line
showing previous invalid interpreter. Now, Open this list and select the Python
Interpreter(in my case, it is Python 3.7). Press "Apply" and "OK" at the bottom and you
are good to go.
Note: It was potentially the issue where Virtual Environment of my Project(B) was not recognizing the already installed and working libraries.
I've installed virtualenv via pip and get this error after creating a new environment:
selenium:~ auser$ virtualenv new
New python executable in new/bin/python
ERROR: The executable new/bin/python is not functioning
ERROR: It thinks sys.prefix is u'/System/Library/Frameworks/Python.framework/ Versions/2.6' (should be '/Users/user/new')
ERROR: virtualenv is not compatible with this system or executable
In my environment:
PYTHONPATH=/System/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages
PATH=/System/Library/Frameworks/Python.framework/Versions/2.6/bin:/Library/Frameworks/Python.framework/Versions/2.6/bin:/Library/Frameworks/Python.framework/Versions/2.6/bin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:/usr/X11/bin
How can I repair this?
Thanks.
Just in case there's someone still seeking for the answer.
I ran into this same problem just today and realized since I already have Anaconda installed, I should not have used pip install virtualenv to install virtual environment as this would give me the error message when trying to initiate it later. Instead, I tried conda install virtualenv then entered virtualenv env_mysite and problem solved.
Like #RyanWilcox mentioned, you might be inadvertently pointing virtualenv to the wrong Python installation. Virtualenv comes with a -p flag to let you specify which interpreter to use.
In my case,
virtualenv test_env
threw the same error as yours, while
virtualenv -p python test_env
worked perfectly.
If you call virtualenv -h, the documentation for the -p flag will tell you which python it thinks it should be using; if it looks wonky, try passing -p python. For reference, I'm on virtualenv 1.11.6.
In case anyone in the future runs into this problem - this is caused by your default Python distribution being conda. Conda has it's own virtual env set up process but if you have the conda distribution of python and still wish to use virtualenv here's how:
Find the other python distribution on your machine: ls -ls /usr/bin/python*
Take note of the availble python version that is not conda and run the code below (note for python 3 and above you have to upgrade virtualenv first): virtualenv -p python2.7(or your python version) flaskapp
I've run across this problem myself. I wrote down the instructions in a README, which I have pasted below....
I have found there are two things that work:
Make sure you're running the latest virtualenv (1.5.1, of this writting)
If you're using a non system Python as your standard Python (which python to check) Forcefully use the System supplied one.
Instead of virtualenv thing use /usr/bin/python2.6 PATH/TO/VIRTUALENV thing (or whatever which
python returned to you - this is what it did for me when I ran into this issue)
I had the same problem and as I see it now, it was caused by a messy Python installation. I have OS X installed for over a year since I bought a new laptop and I have already installed and reinstalled Python for several times using different sources (official binaries, homebrew, official binaries + hand-made adjustments as described here). Don't ask me why I did that, I'm just a miserable newbie believing everything will fix itself after being re-installed.
So, I had a number of different Pythons installed here and there as well as many hardlinks pointing at them inconsistently. Eventually I got sick of all of them and reinstalled OS X carefully cleaned the system from all the Pythons I found using find utility. Also, I have unlinked all the links pointing to whatever Python from everywhere. Then I've installed a fresh Python using homebrew, installed virtualenv and everything works as a charm now.
So, my recipe is:
sudo find / -iname "python*" > python.log
Then analyze this file, remove and unlink everything related to the version of Python you need, reinstall it (I did it with homebrew, maybe official installation will also work) and enjoy. Make sure you unlink everything python-related from /usr/bin and /usr/local/bin as well as remove all the instances of Frameworks/Python.framework/Versions/<Your.Version> in /Library and /System/Library.
It may be a dirty hack, but it worked for me. I prefer not to keep any system-wide Python libraries except pip and virtualenv and create virtual environments for all of my projects, so I do not care about removing the important libraries. If you don't want to remove everything, still try to understand whether your Pythons are, what links point to them and from where. Then think what may cause the problem and fix it.
I ran into a variation of this "not functioning" error.
I was trying to create an environment in a folder that included the path ".../Programming/Developing..." which is actually "/Users/eric/Documents/Programming:Developing/"
and got this error:
ImportError: No module named site
ERROR: The executable env/bin/python2.7 is not functioning
ERROR: It thinks sys.prefix is u'/Users/eric/Documents/Programming:Developing/heroku' (should be u'/Users/eric/Documents/Programming:Developing/heroku/env')
ERROR: virtualenv is not compatible with this system or executable
I tried the same in a different folder and it worked fine, no errors and env/bin has what I expect (activate, etc.).
I got the same problem and I found that it happens when you do not specify the python executable name properly. So for python 2x, for example:
virtualenv --system-site-packages -p python mysite
But for python 3.6 you need to specify the executable name like python3.6
virtualenv --system-site-packages -p python3.6 mysite
On on OSX 10.6.8 leopard, after having "upgraded" to Lion, then downgrading again (ouch - AVOID!), I went through the Wolf Paulus method a few months ago, completely ignorant of python. Deleted python 2.7 altogether and "replaced" it with 3.something. My FTP program stopped working (Fetch) and who knows what else relies on Python 2.7. So at that point I downloaded the latest version of 2.7 from python.org and it's installer got me up and running - until i tried to use virtualenv.
What seems to have worked for me this time was totally deleting Python 2.7 with this code:
sudo rm -R /System/Library/Frameworks/Python.framework/Versions/2.7
removing all the links with this code:
sudo rm /usr/bin/pydoc
sudo rm /usr/bin/python
sudo rm /usr/bin/pythonw
sudo rm /usr/bin/python-config
I had tried to install python with homebrew, but apparently it will not work unless all of XTools is installed, which I have been avoiding, since the version of XTools compatible with 10.6 is ancient and 4GB and mostly all I need is GCC, the compiler, which you can get here.
So I just installed with the latest download from python.org.
Then had to reinstall easy_install, pip, virtualenv.
Definitely wondering when it will be time for a new laptop, but there's a lot to be said for buying fewer pieces of hardware (slave labor, unethical mining, etc).
The above solutions failed for me, but the following worked:
python3 -m venv --without-pip <ENVIRONMENT_NAME>
. <ENVIRONMENT_NAME>/bin/activate
curl https://bootstrap.pypa.io/get-pip.py | python
deactivate
It's hacky, but yes, the core problem really did just seem to be pip.
I did the following steps to get virtualenv working :
Update virtualenv as follows :
==> sudo pip install --upgrade virtualenv
Initialize python3 virtualenv :
==> virtualenv -p python3 venv
I had this same issue, and I can confirm that the problem was with an outdated virtualenv.py file.
It was not necessary to do a whole install --upgrade.
Replacing the virtualenv.py file with the most recent version sufficed.
I also had this problem, and I tried the following method which worked for me:
conda install virtualenv
virtualenv --system-site-packages /anaconda/envs/tensorflow (here envs keeps all the virtual environments made by user)
source /anaconda/envs/tensorflow/bin/activate
Hope it's helpful.
I had this same issue when trying to install py2.7 on a newer system. The root issue was that virtualenv was part of py3.7 and thus was not compatible:
$ virtualenv -p python2.7 env
Running virtualenv with interpreter /usr/local/bin/python2.7
New python executable in /Users/blah/env/bin/python
ERROR: The executable /Users/blah/env/bin/python is not functioning
ERROR: It thinks sys.prefix is u'/Library/Frameworks/Python.framework/Versions/2.7' (should be u'/Users/blah/env')
ERROR: virtualenv is not compatible with this system or executable
$ which virtualenv
/Library/Frameworks/Python.framework/Versions/3.7/bin/virtualenv
# install proper version of virtualenv
$ pip2.7 install virtualenv
$ /Library/Frameworks/Python.framework/Versions/2.7/bin/virtualenv -p python2.7 env
$ . ./env/bin/activate
(env) $
Open terminal and type /Library/Frameworks/Python.framework/Versions/
then type ls /Library/Frameworks/Python.framework/Versions/2.7/bin/
if you are using Python2(or any other else).
Edit ~/.bash_profile and add the following line:
export PATH=$PATH:/Library/Frameworks/Python.framework/Versions/2.7/bin/
cat ~/.bash_profile
In my case the content of ~/.bash_profile is as follows:
export PATH=$PATH:/Library/Frameworks/Python.framework/Versions/2.7/bin/
Now the virtualenv command should work.
If you continue to have trouble with virtualenv, you might try pythonbrew, instead. It's an alternate solution to the same problem. It works more like Ruby's rvm: It builds and creates an entire instance of Python, under $HOME/.pythonbrew, and then sets up some bash functions that allow you to switch easily between versions. Where virtualenv shadows the system version of Python, using symbolic links as part of its solution, pythonbrew builds entirely self-contained installations of Python.
I used virtualenv for years. It's a decent solution, but I've switched to pythonbrew lately. Having completely self-contained Python instances means that installing a new one takes awhile (since pythonbrew actually compiles Python from scratch), but the self-contained nature of each installation appeals to me. And disk is cheap.