Python Using Pip


title: Python Using Pip

We have seen how to use import statements to import various modules and to use them in our programs. Python itself comes with several built-in modules, but the Python community has more to offer.

It’s the modules that make Python so powerful!

Third party modules add so much more functionality to Python. Now we would learn how to install these modules so that we can use those in our programs.

The simplest way to install these modules is by using pip.

pip install <module_name>

If you have used npm, then you can think of it as npm of Python.

Side note: The difference is that with npm, npm install by default installs packages locally to a project, whereas pip install by default installs globally. To install modules locally, you need to create and activate what is called a virtual environment, so pip install installs to the folder where that virtual environment is located, instead of globally (which may require administrator privileges).

Last time, in import-statements wiki we used requests module as an example. As it is a third party module we have to install it separately after installing python.

Installing it would be as simple as pip install requests . You can even pass various arguments along with it. The one that you’ll come across more often is --upgrade. You can upgrade a python module by :

pip install <module_name> --upgrade

For example, to upgrade the requests module to its latest version would be as simple as pip install requests --upgrade.
To update pip itself, you can use pip install --upgrade pip

To find other useful commands for pip, use pip help. This will give you a list of useful commands and arguments you can use, such as uninstall, list or search.

Before using pip, you will need to install it (it’s quite simple). You can install it from here

Just click on the link. And save the file as get-pip.py Please don’t forget the .py extension. And run it.

An alternative to using pip would be to try easy_install.

Using easy_install is also simple. The syntax is:

easy_install <module_name>

However, pip is more popular than using easy_install, and easy_install is deprecated.

Note: On some systems where both Python 2 & Python 3 is installed, pip and pip3 will do different things. pip installs the Python 2 version of the package, and pip3 will install the Python 3 version of the package. For more information on the difference between Python 2 & 3, see this guide.
You can check the pip version by doing pip --version and/or pip3 --version:

pip3 --version pip 18.0 from /usr/local/lib/python3.5/dist-packages/pip (python 3.5)

We can also create a txt file containing a list of modules which should be installed using pip.
For example, we could create the file requirements.txt and its content:

Kivy-Garden==0.1.4 macholib==1.5.1 idna==2.6 geoip2nation==0.1.2 docutils>=0.14 Cython

In this file, we could also set a version for the installation.
After this, by invoking pip with:

pip install -r <FILE CONTAINING MODULES> OR IN OUR CASE pip install -r requirements.txt

Should install all the modules listed on the file.

If you need to know which packages you have installed (along with their versions) you
can use the list command:

pip list

This will come in handy when installing packages with prerequisites such as torch or tensorflow.

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