How to Install Python Packages? – Part II

Learn about modules and packages with Part I.

Bonus: dir()function

We can use the built-in function dir() to find which names a module defines. It returns a sorted list of strings.

import arithmetic
dir(arithmetic)

dir.py hosted with ❤ by GitHub

Output:

[‘__builtins__’,

‘__cached__’,

‘__doc__’,

‘__file__’,

‘__loader__’,

‘__name__’,

‘__package__’,

‘__spec__’,

‘addition’,

‘division’,

‘factorial’,

‘multiply’]

dir()function | 61

Here, we can see a sorted list of names within the module arithmetic. All other names that begin with an underscore are default Python attributes associated with the module (we did not define them).

Without arguments, dir() lists the names we have defined currently:

a = 1
b = 'string'
import arithmetic
dir()

Without_arguments.py hosted with ❤ by GitHub

Output:

[‘__builtins__’,

‘a’,

‘arithmetic’,

‘b’,

‘exit’,

‘Quit’]

Note that it lists all types of names: variables, modules, functions, etc. The dir() does not list the names of built-in functions and variables. They are defined in the standard module builtins. We can list them by passing builtins as an argument in the dir().

import builtins
dir(builtins)

builtins.py hosted with ❤ by GitHub

Output:

‘ArithmeticError’, ‘AssertionError’,

‘AttributeError’, ‘BaseException’,

‘BlockingIOError’, ‘BrokenPipeError’,

‘BufferError’, ‘BytesWarning’, ‘ChildProcessError’,

‘ConnectionAbortedError’, ‘ConnectionError’,

‘ConnectionRefusedError’, ‘ConnectionResetError’,

‘DeprecationWarning’, ‘EOFError’, ‘Ellipsis’,

‘EnvironmentError’, ‘Exception’, ‘False’,

‘SyntaxError’, … ]

Now, let us find out answers to some common questions of the users next. This could help you with an answer in case you are facing the same issues with Python packages and need help.

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Stay tuned for the next installment to learn how to resolve frequent user queries.

Originally posted on QuantInsti blog.