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No module named pandas but pandas is already installed in linux

I have two python distributions(python2.7,python3.6) and in both I have installed pandas and numpy as well but cant use
These are the errors caused when i tried to import pandas
in python 2.7
File "/usr/local/lib/python2.7/dist-packages/pandas/init.py", line 19, in
"Missing required dependencies {0}".format(missing_dependencies))
ImportError: Missing required dependencies ['numpy']
then imported numpy
ImportError:
Importing the multiarray numpy extension module failed. Most
likely you are trying to import a failed build of numpy.
If you're working with a numpy git repo, try git clean -xdf (removes all
files not under version control). Otherwise reinstall numpy.
Original error was: cannot import name multiarray
in python 3.6
Traceback (most recent call last):
File "", line 1, in
ModuleNotFoundError: No module named 'pandas'

Most of these cases, the problem is that you are installing pandas in another environment. The easy solution here is using Anaconda.
Anaconda is focused on environments. First, you should choose installation of python2 or python3. Then, you can install this version of Anaconda in Linux: https://www.anaconda.com/download/#linux
For example:
64-Bit (x86) Installer (622 MB) Python3:
$ wget https://repo.anaconda.com/archive/Anaconda3-5.2.0-Linux-x86_64.sh
Then you need, install in your system:
$ bash Anaconda3-5.2.0-Linux-x86_64.sh
Be cautious in the interactive dialog in order to install Anaconda. Remember the route of the installation.
When you have Anaconda in a folder named: anaconda 3 (for example). go to route: .../anaconda3/bin.
Now, you should execute:
$ source activate
Now you are in base environment, you can install the packages that you need (pandas and numpy are install by default). However, I recommend you create a new environment for each new proyect (see https://conda.io/docs/_downloads/conda-cheatsheet.pdf).
Imagine that you have (base) environment. In this environment try:
$ python
The first message gives you the python version. Anyway you can try:
>>> import sys
>>> sys.version
In order to know the version that you are using.

gmpy2 installs but can't find libmpc.so.3

I want to use gmpy2 with python 2.7 but when I try to import it I get:
>>> import gmpy2
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ImportError: libmpc.so.3: cannot open shared object file: No such file or directory
I installed gmpy2 using pip: pip install -user gmpy2 and the install looks ok apart from saying
Could not find .egg-info directory in install record for gmpy2
but after that it says that the install was a success.
I have installed MPC (1.0.3), GMP (6.1.1) and MPFR (3.1.4) and they all work, by which I mean I can call gcc foo.c -lmpc and gcc bar.c -lmpfr and the code compiles and works as expected. I've also got gmpy working using pip install. I think the problem will be to do with them not being installed in the default directories as I don't have sudo rights.
The directory where libmpc.so.3 is located is in the gcc call that pip spits out, I've also set CPATH and CPPFLAGS to look in my_prefix/include and LDFLAGS to look my_prefix/lib.
I don't really want to use the functionality from MPC so if there's a simple option to not install that part of gmpy2 I'd be happy with that.
I'm really confused, I've had it that pip fails to build a library and I've gone away and installed dependencies but normally once a library is passed pip it works.

I maintain gmpy2 and there are a couple of command line options that can be passed to setup.py that may help. I can't test the pip syntax right now but here are some options:
--shared=/path/to/gmp,mpfr,mpc will configure gmpy2 to load the libraries from the specified directory.
--static or --static=/path/to/gmp,mpfr,mpc will create a statically linked version of gmpy2 if the proper libraries can be found.
You can also try a build using setup.py directly. It may produce better error messages. Again, untested command:
python setup.py build_ext --static=/path/to/gmp,mpfr,mpc should compile a standalone, staticly linked gmpy2.so which will need to moved to the appropriate location.
Update
I've been able to test the options to pip.
If you are trying to use versions of GMP, MPFR, and MPC that are not those provided by the Linux distribution, you will need to specify the location of the new files to the underlying setup.py that is called by pip. For example, I have updated versions installed locally in /home/case/local. The following command will configure gmpy2 to use those versions:
pip install --install-option="--shared=/home/case/local" --user gmpy2
To compile a statically linked version (for example, to simplify distribution to other systems in cluster), you should use the following:
pip install --install-option="--static=/home/case/local" --user gmpy2
setup.py will use the specified base directory to configure the correct INCLUDE path (/home/case/local/include) and runtime library path (/home/case/local/lib).

Try to do the following as it might me fixed in an older version:
pip install --upgrade setuptools pip
pip uninstall gmpy2
pip install gmpy2

Python error message "Incompatible library version" libxml and etree.so

Update 2:
the main problem turned out to be a different one from what I had thought it was, and asked for help here. I moved the new question to a new post:
Install custom python package in virtualenv
Update:
ok, so I screwed up my non-virtualenv by accident.
The non-virtualenv (normal bash) I could easily fix by removing the manually installed (via pip) lxml and running
conda install lxml --force
But for some reason, that doesn't work in the virtualenv.
There, running
conda install lxml --force
works without error message, but when I run python and simply say
>>> import lxml
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ImportError: No module named lxml
Any suggestions??
old message:
I'm trying to use virtualenv for my python flask application.
The python code runs perfectly fine without the virtualenv.
I've installed the packages I need in the virtualenv, but I after installing lxml via
pip install lxml
Installing collected packages: lxml
Successfully installed lxml-3.6.0
I get the following error message when running my code:
File "/Users/XXX/xxx/flask-aws/lib/python2.7/site-packages/docx-0.2.4-py2.7.egg/docx.py", line 17, in <module>
from lxml import etree
ImportError: dlopen(/Users/XXX/xxx/flask-aws/lib/python2.7/site-packages/lxml/etree.so, 2): Library not loaded: libxml2.2.dylib
Referenced from: /Users/XXX/xxx/flask-aws/lib/python2.7/site-packages/lxml/etree.so
Reason: Incompatible library version: etree.so requires version 12.0.0 or later, but libxml2.2.dylib provides version 10.0.0
I have seen other people report similar problems at stackoverflow, and one guy remarked that the problem might related to the virtualenv, but there was no solution.
Once again: The python code runs perfectly fine without virtualenv! But inside virtualenv, I can't get it to work.
I'm using Anaconda Python 2.7 on a Mac.
I'd appreciate any help guys!

I had the same error and stumbled upon this link, after searching for the incompatible library error "libxml2.2.dylib provides version 10.0.0"
Installing libxml2 that worked for me:
brew install libxml2
brew link --force libxml2

Solution that works for me in virtual environment is to force pip to recompile lxml:
pip install lxml --force-reinstall --ignore-installed --no-binary :all:

Error when importing python igraph in OSX 10.10.5 by anaconda (libxml2.2.dylib)

I installed the python igraph library for anaconda following the directions in this thread installing python igraph, So the C core library and the python package were successfully installed. However, when I tried to import the igraph library in python, I am getting the following error
>>> import igraph
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/Users/user/anaconda/lib/python2.7/site-packages/igraph/__init__.py", line 34, in <module>
from igraph._igraph import *
ImportError: dlopen(/Users/user/anaconda/lib/python2.7/site-packages/igraph/_igraph.so, 2): Library not loaded: libxml2.2.dylib
Referenced from: /Users/user/anaconda/lib/python2.7/site-packages/igraph/_igraph.so
Reason: Incompatible library version: _igraph.so requires version 12.0.0 or later, but libxml2.2.dylib provides version 10.0.0
Looking for similar threads, I found a similar issue here Installation of python igraph with lxml problem. However, there is not a clear way on how to solve this issue. Does anyone know how to fix it? Thanks in advance.

Anaconda Python is weird - it ships with its own version of libxml2 and when you run pip install python-igraph, igraph is probably linked against it. However, when you try to import igraph, the linker finds the system-wide libxml2, which has a lower ABI version, so that's why you see the error message.
The workaround for this is to ensure that during the compilation stage, Anaconda Python's libxml2 is not picked up by the compiler. setup.py in the Python interface of igraph actually contains this workaround - it tries to detect when you are compiling igraph against Anaconda Python on OS X and then it tweaks the environment a bit to ensure that the linker picks up the right version of libxml2. However, this workaround is enabled only if you do not have the C core of igraph installed on your machine - the installer will download the C core, tweak the environment to work around Anaconda Python, then compile the C core and the Python interface together in one single step.
So, the solution is probably one of the following:
Move Anaconda Python's libxml2 out of the way (or maybe rename xml2-config from Anaconda Python's distribution temporarily), then compile and install the C core from Homebrew. (Use brew unlink igraph, brew uninstall igraph, brew install igraph to be on the safe side). Then you can run pip install python-igraph.
Remove Homebrew's igraph entirely and just run pip install python-igraph - it will download the C core, perform the necessary tweaks and then compile everything.

I had exactly the same issue and installing/force linking libxml2 worked for me:
brew install libxml2
brew link --force libxml2
Others also report the same solution and it appears to be working.

Importing opencv and getting numpy.core.multiarray failed to import

Trying to install OpenCV and running into an issue where attempting to import cv2 results in this output -
RuntimeError: module compiled against API version 9 but this version of numpy is 7
Traceback (most recent call last):
File "<pyshell#4>", line 1, in <module>
import cv2
ImportError: numpy.core.multiarray failed to import
I'm running on Windows 7 x64, Python v 2.7.9
Thanks!

The error is telling you that you have an out of date version of numpy. If you used pip to install things you can simply run pip install numpy -U, or download the appropriate version from their website.

In case
pip install -U numpy
doesn't work (even with sudo), you may want to make sure you're using the right version of numpy. I had the same "numpy.core.multiarray failed to import" issue, but it was because I had 1.6 installed for the version of Python I was using, even though I kept installing 1.8 and assumed it was installing in the right directory.
I found the bad numpy version by using the following command in my Mac terminal:
python -c "import numpy;print numpy.version;print numpy.file";
This command gave me the version and location of numpy that I was using (turned out it was 1.6.2). I went to this location and manually replaced it with the numpy folder for 1.8, which resolved my "numpy.core.multiarray failed to import" issue. Hopefully someone finds this useful!

I had a similar problem and I solved it by downgrading my numpy version.
What I did was:
pip install opencv-python
pip uninstall numpy
pip install numpy=1.18
This has worked for me using
Python 3.7
opencv-python 4.4.0.46
numpy 1.18.0

linux: sudo apt-get install python-numpy

if you are using ubuntu bionic beaver then try running: sudo apt-get install python-numpy
had the same issue, resolve by running the above command.
Hope it helps

In your environment you can try this command:
conda uninstall numpy
conda install -c conda-forge numpy

I use Python 3.7 # RPI 4.
For opencv to install properly I had to install the listed libraries below.
(Not every package was actually installed, after request)
Regarding Numpy, I think one should stick to the latest version.
For me what worked is to uninstall the existing version 1.16.2 and stick with the current stable 1.21.2.
Stackoverflow topic at missing libraries here: ImportError: libcblas.so.3: cannot open shared object file: No such file or directory.