Issue 1:
I was trying to import numpy but came out with this problem, i tried to reinstall numpy but it's still not working, any ideas?

Here's the issue-

import numpy

Traceback (most recent call last):

File "/usr/local/lib/python3.5/dist-packages/numpy/core/init.py", line 17, in

from . import multiarray

File "/usr/local/lib/python3.5/dist-packages/numpy/core/multiarray.py", line 14, in

from . import overrides

File "/usr/local/lib/python3.5/dist-packages/numpy/core/overrides.py", line 7, in

from numpy.core._multiarray_umath import (

ImportError: /usr/local/lib/python3.5/dist-packages/numpy/core/_multiarray_umath.cpython-35m-arm-linux-gnueabihf.so: undefined symbol: cblas_sgemm

During handling of the above exception, another exception occurred:

Traceback (most recent call last):

File "<pyshell#0>", line 1, in

import numpy

File "/usr/local/lib/python3.5/dist-packages/numpy/init.py", line 142, in

from . import core

File "/usr/local/lib/python3.5/dist-packages/numpy/core/init.py", line 47, in

raise ImportError(msg)

ImportError:

IMPORTANT: PLEASE READ THIS FOR ADVICE ON HOW TO SOLVE THIS ISSUE!

Importing the numpy c-extensions failed.

Try uninstalling and reinstalling numpy.

If you have already done that, then:

Check that you expected to use Python3.5 from "/usr/bin/python3",

and that you have no directories in your PATH or PYTHONPATH that can

interfere with the Python and numpy version "1.17.2" you're trying to use.

If (1) looks fine, you can open a new issue at

https://github.com/numpy/numpy/issues. Please include details on:

how you installed Python

how you installed numpy

your operating system

whether or not you have multiple versions of Python installed

if you built from source, your compiler versions and ideally a build log

If you're working with a numpy git repository, try git clean -xdf

(removes all files not under version control) and rebuild numpy.

Note: this error has many possible causes, so please don't comment on

an existing issue about this - open a new one instead.

Original error was: /usr/local/lib/python3.5/dist-packages/numpy/core/_multiarray_umath.cpython-35m-arm-linux-gnueabihf.so: undefined symbol: cblas_sgemm

Issue 2:
This is on installing numpy on raspberry pi 3. I used the Noobs latest version and so using Raspbian stretch. Python was already installed, and I think numpy was already included. At the time, I think that import numpy was working well.

I installed openCV and it didn't work for a while as I had not put some necessary modules, but finally got it to work. So far so good.

Later I was trying to install matplotlib, and this didn't go very smoothly. I made a number of attempts where the message in the title was already flagged. I finally manage to get the import matplotlib to work, but then numpy stopped importing. Now I cannot import either matplotlib or numpy, despite having uninstalled numpy (pip3 uninstall numpy) and reinstalled:

/home/pi/.local/lib/python3.5/site-packages/numpy/tests/test_warnings.py

/home/pi/.local/lib/python3.5/site-packages/numpy/version.py

Proceed (y/n)? y

Successfully uninstalled numpy-1.16.1

pi@raspberrypi:~ $ pip3 install numpy

Collecting numpy

Using cached https://www.piwheels.org/simple/numpy/numpy-1.16.1-cp35-cp35m-linux_armv7l.whl

Installing collected packages: numpy

Successfully installed numpy-1.16.1

pi@raspberrypi:~ $

Prior to uninstalling numpy, I did try to install without uninstalling, and downloaded the cached file mentioned.

Now, I cannot import numpy or matplotlib and for both get a similar error and the message telling me to raise this new issue which I am doing now.

import numpy

Traceback (most recent call last):

File "/home/pi/.local/lib/python3.5/site-packages/numpy/core/init.py", line 16, in

from . import multiarray

File "/home/pi/.local/lib/python3.5/site-packages/numpy/core/multiarray.py", line 12, in

from . import overrides

File "/home/pi/.local/lib/python3.5/site-packages/numpy/core/overrides.py", line 6, in

from numpy.core._multiarray_umath import (

ImportError: /home/pi/.local/lib/python3.5/site-packages/numpy/core/_multiarray_umath.cpython-35m-arm-linux-gnueabihf.so: undefined symbol: cblas_sgemm

During handling of the above exception, another exception occurred:

Traceback (most recent call last):

File "<pyshell#0>", line 1, in

import numpy

File "/home/pi/.local/lib/python3.5/site-packages/numpy/init.py", line 142, in

from . import core

File "/home/pi/.local/lib/python3.5/site-packages/numpy/core/init.py", line 47, in

raise ImportError(msg)

ImportError:

IMPORTANT: PLEASE READ THIS FOR ADVICE ON HOW TO SOLVE THIS ISSUE!

Importing the multiarray numpy extension module failed. Most

likely you are trying to import a failed build of numpy.

Here is how to proceed:

If you're working with a numpy git repository, try git clean -xdf

(removes all files not under version control) and rebuild numpy.

If you are simply trying to use the numpy version that you have installed:

your installation is broken - please reinstall numpy.

If you have already reinstalled and that did not fix the problem, then:

Check that you are using the Python you expect (you're using /usr/bin/python3),

and that you have no directories in your PATH or PYTHONPATH that can

interfere with the Python and numpy versions you're trying to use.

If (1) looks fine, you can open a new issue at

https://github.com/numpy/numpy/issues. Please include details on:

how you installed Python

how you installed numpy

your operating system

whether or not you have multiple versions of Python installed

if you built from source, your compiler versions and ideally a build log

Note: this error has many possible causes, so please don't comment on

an existing issue about this - open a new one instead.

Original error was: /home/pi/.local/lib/python3.5/site-packages/numpy/core/_multiarray_umath.cpython-35m-arm-linux-gnueabihf.so: undefined symbol: cblas_sgemm

import matplotlib

Traceback (most recent call last):

File "/home/pi/.local/lib/python3.5/site-packages/numpy/core/init.py", line 16, in

from . import multiarray

File "/home/pi/.local/lib/python3.5/site-packages/numpy/core/multiarray.py", line 12, in

from . import overrides

File "/home/pi/.local/lib/python3.5/site-packages/numpy/core/overrides.py", line 6, in

from numpy.core._multiarray_umath import (

ImportError: /home/pi/.local/lib/python3.5/site-packages/numpy/core/_multiarray_umath.cpython-35m-arm-linux-gnueabihf.so: undefined symbol: cblas_sgemm

During handling of the above exception, another exception occurred:

Traceback (most recent call last):

File "<pyshell#1>", line 1, in

import matplotlib

File "/home/pi/.local/lib/python3.5/site-packages/matplotlib/init.py", line 141, in

from . import cbook, rcsetup

File "/home/pi/.local/lib/python3.5/site-packages/matplotlib/cbook/init.py", line 33, in

import numpy as np

File "/home/pi/.local/lib/python3.5/site-packages/numpy/init.py", line 142, in

from . import core

File "/home/pi/.local/lib/python3.5/site-packages/numpy/core/init.py", line 47, in

raise ImportError(msg)

ImportError:

IMPORTANT: PLEASE READ THIS FOR ADVICE ON HOW TO SOLVE THIS ISSUE!

Importing the multiarray numpy extension module failed. Most

likely you are trying to import a failed build of numpy.

Here is how to proceed:

If you're working with a numpy git repository, try git clean -xdf

(removes all files not under version control) and rebuild numpy.

If you are simply trying to use the numpy version that you have installed:

your installation is broken - please reinstall numpy.

If you have already reinstalled and that did not fix the problem, then:

Check that you are using the Python you expect (you're using /usr/bin/python3),

and that you have no directories in your PATH or PYTHONPATH that can

interfere with the Python and numpy versions you're trying to use.

If (1) looks fine, you can open a new issue at

https://github.com/numpy/numpy/issues. Please include details on:

how you installed Python

how you installed numpy

your operating system

whether or not you have multiple versions of Python installed

if you built from source, your compiler versions and ideally a build log

Note: this error has many possible causes, so please don't comment on

an existing issue about this - open a new one instead.

Original error was: /home/pi/.local/lib/python3.5/site-packages/numpy/core/_multiarray_umath.cpython-35m-arm-linux-gnueabihf.so: undefined symbol: cblas_sgemm

I hope this helps and that it will eventually contribute to making the installation of these two packages easier in the future.

Thanks,

Thomas