Set Syntax

August 7, 2021

Python use symbols to initialize variable. [] creates a new empty list, () creates a new tuple, {} creates a new empty dictionary. These are well documented.

{*()} creates a new set. The syntax to create a new set is set(<iter>). The starred expression, *() unpacks the value into the set.

Code Examples

In [1]: {}
Out[1]: {}

In [2]: []
Out[2]: []

In [3]: type([])
Out[3]: list

In [4]: type({})
Out[4]: dict

In [5]: {*()}
Out[5]: set()

In [6]: type({*()})
Out[6]: set

In [7]: {*(1, 1)}
Out[7]: {1}

In [8]: {*[1, 1]}
Out[8]: {1}

In [9]: {*{1, 1}}
Out[9]: {1}

In [10]: *[1, 2]
  File "<ipython-input-10-7825c5ac490d>", line 1
    *[1, 2]
    ^
SyntaxError: can't use starred expression here

python