Exploring Python#

Whether you use IDLE or the interactive shell, there are some useful functions to explore Python.


help() has two different modes. When you type help(), you call the help system, which you can use to get information about modules, keywords, and other topics. When you are in the help system, you will see a prompt with help>. You can now enter a module name, for example float, to search the Python documentation for that type.

help() is part of the pydoc library, which provides access to the documentation built into Python libraries. Since every Python installation comes with full documentation, you have all the documentation at your fingertips even offline.

Alternatively, you can use help() more specifically by passing a type or variable name as a parameter, for example:

>>> x = 4.2
>>> help(x)
Help on float object:

class float(object)
 |  float(x=0, /)
 |  Convert a string or number to a floating point number, if possible.
 |  Methods defined here:
 |  __abs__(self, /)
 |      abs(self)

dir(), globals() and locals()#

dir() is another useful function that lists objects in a specific namespace. If you use it without parameters, you can find out which methods and data are available locally. Alternatively, it can also list objects for a module or type.

>>> dir()
['__annotations__', '__builtins__', '__doc__', '__loader__', '__name__', '__package__', '__spec__', 'x']
>>> dir(x)
['__abs__', '__add__', '__bool__', '__ceil__', '__class__', '__delattr__', '__dir__', '__divmod__', '__doc__', '__eq__', '__float__', '__floor__', '__floordiv__', '__format__', '__ge__', '__getattribute__', '__getformat__', '__getnewargs__', '__getstate__', '__gt__', '__hash__', '__init__', '__init_subclass__', '__int__', '__le__', '__lt__', '__mod__', '__mul__', '__ne__', '__neg__', '__new__', '__pos__', '__pow__', '__radd__', '__rdivmod__', '__reduce__', '__reduce_ex__', '__repr__', '__rfloordiv__', '__rmod__', '__rmul__', '__round__', '__rpow__', '__rsub__', '__rtruediv__', '__setattr__', '__sizeof__', '__str__', '__sub__', '__subclasshook__', '__truediv__', '__trunc__', 'as_integer_ratio', 'conjugate', 'fromhex', 'hex', 'imag', 'is_integer', 'real']

In contrast to dir(), both globals() and locals() display the values associated with the objects. Currently, both functions return the same thing:

>>> globals()
{'__name__': '__main__', '__doc__': None, '__package__': None, '__loader__': <class '_frozen_importlib.BuiltinImporter'>, '__spec__': None, '__annotations__': {}, '__builtins__': <module 'builtins' (built-in)>, 'x': 4.2}