问题
What's the difference between () vs [] vs {} in Python?
They're collections? How can I tell when to use which?
回答1:
() - tuple
A tuple is a sequence of items that can't be changed (immutable).
[] - list
A list is a sequence of items that can be changed (mutable).
{} - dictionary or set
A dictionary is a list of key-value pairs, with unique keys (mutable). From Python 2.7/3.1, {} can also represent a set of unique values (mutable).
回答2:
- () is a tuple: An immutable collection of values, usually (but not necessarily) of different types.
- [] is a list: A mutable collection of values, usually (but not necessarily) of the same type.
- {} is a dict: Use a dictionary for key value pairs.
For the difference between lists and tuples see here. See also:
- Python Tuples are Not Just Constant Lists
回答3:
() - tuple
[] - list
{} - dictionary
All Python tutorials should cover this. Here is a good place to start.
回答4:
In addition to the tuple, list and dict given by the other answers, {} also denotes a set literal in python 2.7 and python 3.1. (This makes sense because set elements act like the keys of a dict).
来源：https://stackoverflow.com/questions/4407873/whats-the-difference-between-vs-vs