1.20 installing packages

What is meaning of installing a python package?

def foo():
    pass

foo()

Above we used the function foo which was defined above in the same file where it was called. However, if the foo was defined not in the same file, but in some other file, we would have to import the foo function from that file. That file containing foo function can be located anywhere in the hard drive/storage of our machine/computer. If python is able to ‘see’ that file and consequently the foo function in that file, you can import foo from that file. But if python is not able to see that file, even if it is located somewhere in your computer, you can not import that function. This applies not only to functions by to every python object like variables, classes etc. The process of putting the required files in required format at the required location can be termed as installing a library/module/package in python. When we say that we want to install a library say numpy in python, it means we want all the files of this library at a place in our computer so that python can see it. Moreover, the files should be in such a form that we can import our desired functions from them.

putting module in cwd

A simpler solution of installing a package/library is to simply put in our current working directory. This is because if we print sys.path, the first directory is the current working directory. This means, whenever we try to import something, python will look into current working directory. Therefore, if we put some file/package/library in our current working directory, we can simply import that library without any problem.

using site

Putting a lot of libraries/packages in our current working library can clutter current working direcotry. This is because we may need hundred of libraries to work with. One solution is to place those packages at any place in our desired location in our machine, and then import that package from that location. We can add the location of that package into python’s path during runtime using site.addsitedir function.

import site
site.addsitedir('path/to/my/package')

pip

An easy and one of the most commonly used tool to install a package is using pip. We can do this in the command prompt. Remember that pip installs the package in site_packages directory of python.

pip install easy_mpl

pip install easy_mpl==0.21.3

pip install -update easy_mpl

pip install easy_mpl[all]

conda

# -e .