A common error you may encounter when using Python is modulenotfounderror: no module named ‘numpy’. This error occurs when Python cannot detect the NumPy library in your current environment. This tutorial goes through the exact steps to troubleshoot this error for the Windows, Mac and Linux operating systems.

ModuleNotFoundError: no module named ‘numpy’

What is ModuleNotFoundError?

The ModuleNotFoundError occurs when the module you want to use is not present in your Python environment. There are several causes of the modulenotfounderror:

The module’s name is incorrect, in which case you have to check the name of the module you tried to import. Let’s try to import the re module with a double e to see what happens:

import ree
---------------------------------------------------------------------------
ModuleNotFoundError                       Traceback (most recent call last)
1 import ree

ModuleNotFoundError: No module named 'ree'

To solve this error, ensure the module name is correct. Let’s look at the revised code:

import re

print(re.__version__)
2.2.1

You may want to import a local module file, but the module is not in the same directory. Let’s look at an example package with a script and a local module to import. Let’s look at the following steps to perform from your terminal:

mkdir example_package

cd example_package

mkdir folder_1

cd folder_1

vi module.py

Note that we are using Vim to create the module.py file in this example. You can use your preferred file editor, such as Emacs or Atom. In module.py, we will import the re module and define a simple function that prints the re version:

import re

def print_re_version():

    print(re.__version__)

Close the module.py, then complete the following commands from your terminal:

cd ../

vi script.py

Inside script.py, we will try to import the module we created.

import module

if __name__ == '__main__':

    mod.print_re_version()

Let’s run python script.py from the terminal to see what happens:

Traceback (most recent call last):
  File "script.py", line 1, in <module>
    import module
ModuleNotFoundError: No module named 'module'

To solve this error, we need to point to the correct path to module.py, which is inside folder_1. Let’s look at the revised code:

import folder_1.module as mod

if __name__ == '__main__':

    mod.print_re_version()

When we run python script.py, we will get the following result:

2.2.1

Lastly, you can encounter the modulenotfounderror when you import a module that is not installed in your Python environment.

What is Numpy?

NumPy is the fundamental Python library for scientific computing. The library provides a multidimensional array object, the ndarray and routines and operations for manipulating multidimensional arrays. NumPy does not come installed automatically with Python. The easiest way to install NumPy is to use the package manager for Python called pip. The following installation instructions are for the major Python version 3.

How to Install Numpy on Windows Operating System

To install NumPy using pip on Windows, you need to download and install Python on your PC. Ensure you select the install launcher for all users and Add Python to PATH checkboxes. The latter ensures the interpreter is in the execution path. Pip is automatically installed on Windows for Python versions 2.7.9+ and 3.4+.

You can install pip on Windows by downloading the installation package, opening the command line and launching the installer. You can install pip via the CMD prompt by running the following command.

python get-pip.py

You may need to run the command prompt as administrator. Check whether the installation has been successful by typing.

pip --version

To install numpy with pip, run the following command from the command prompt.

pip3 install numpy

How to Install Numpy on Mac Operating System

Open a terminal by pressing command (⌘) + Space Bar to open the Spotlight search. Type in terminal and press enter.

To get pip, first ensure you have installed Python3:

python3 --version
Python 3.8.8

Download pip by running the following curl command:

curl https://bootstrap.pypa.io/get-pip.py -o get-pip.py

The curl command allows you to specify a direct download link, and using the -o option sets the name of the downloaded file.

Install pip by running:

python3 get-pip.py

From the terminal, use the pip3 command to install numpy:

pip3 install numpy

How to Install Numpy on Linux Operating Systems

All major Linux distributions have Python installed by default. However, you will need to install pip. You can install pip from the terminal, but the installation instructions depend on the Linux distribution you are using. You will need root privileges to install pip and numpy. Open a terminal and use the commands relevant to your Linux distribution to install pip.

Installing pip for Ubuntu, Debian, and Linux Mint

sudo apt install python-pip3

Installing pip for CentOS 8 (and newer), Fedora, and Red Hat

sudo dnf install python-pip3

Installing pip for CentOS 6 and 7, and older versions of Red Hat

sudo yum install epel-release

sudo yum install python-pip3

Installing pip for Arch Linux and Manjaro

sudo pacman -S python-pip

Installing pip for OpenSUSE

sudo zypper python3-pip

Once you have installed pip, you can install numpy using:

pip3 install numpy

Check NumPy Version

Once you have successfully installed NumPy, you can use two methods to check the version of NumPy. First, you can use pip from your terminal:

pip show numpy
Name: numpy
Version: 1.18.5
Summary: NumPy is the fundamental package for array computing with Python.
Home-page: https://www.numpy.org
Author: Travis E. Oliphant et al.
Author-email: None
License: BSD
Location: /Users/Yusufu.Shehu/opt/anaconda3/lib/python3.8/site-packages
Requires: 
Required-by: tifffile, tensorflow, tensorboard, tables, statsmodels, seaborn, scipy, scikit-learn, scikit-image, PyWavelets, pyerfa, patsy, pandas, opt-einsum, numexpr, numba, mlxtend, mkl-random, mkl-fft, matplotlib, Keras, Keras-Preprocessing, Keras-Applications, imbalanced-learn, imageio, h5py, gym, gensim, Bottleneck, bokeh, bkcharts, astropy

Second, within your python program, you can import numpy and then reference the __version__ attribute:

import numpy as np

print(np.__version__)
1.18.5

Installing Numpy Using Anaconda

Anaconda is a distribution of Python and R for scientific computing and data science. Anaconda comes with numpy and other relevant Python libraries for data science and machine learning. You can install Anaconda by going to the installation instructions.

You can install numpy in your conda environment using the following command from your terminal or command prompt:

conda install -c anaconda numpy

Summary

Congratulations on reading to the end of this tutorial. The modulenotfounderror occurs if you misspell the module name, incorrectly point to the module path or do not have the module installed in your Python environment. If you do not have the module installed in your Python environment, you can use pip to install the package. However, you must ensure you have pip installed on your system. You can also install Anaconda on your system, which comes with numpy.

For further reading on installing data science and machine learning libraries, you can go to the articles:

For further reading on using numpy arrays go to the article: How-to Guide for Python NumPy Where Function.

Go to the online courses page on Python to learn more about Python for data science and machine learning.

Have fun and happy researching!