Dictionary DICT
dict1 = {"key1":"value1", "key2":"value2" }
Constructor:
| dict() -> new empty dictionary
| dict(mapping) -> new dictionary initialized from a mapping object's
| (key, value) pairs
| dict(iterable) -> new dictionary initialized as if via:
| d = {}
| for k, v in iterable:
| d[k] = v
| dict(**kwargs) -> new dictionary initialized with the name=value pairs
| in the keyword argument list. For example: dict(one=1, two=2)
for example:
-------------------------------------------------------------------
Dictionary = assignment is assignment by reference, for example:
>>> dict1={}
>>> dict1
{}
>>> dict2
{0: 'hello world', 1: 'hello world', 2: 'hello world', 3: 'hello world', 4: 'hello world', 5: 'hello world', 6: 'hello world', 7: 'hello world', 8: 'hello world', 9: 'hello world'}
>>> dict1.clear()
>>> dict2
{0: 'hello world', 1: 'hello world', 2: 'hello world', 3: 'hello world', 4: 'hello world', 5: 'hello world', 6: 'hello world', 7: 'hello world', 8: 'hello world', 9: 'hello world'}
>>> dict2.clear()
>>> dict2
{}
dict2 = dict1.copy()//Full copy, the value of dict2 is in the new memory area
-------------------------------------------------------------------
gather
Mutable collection set features: can not be repeated, the order is rearranged
Immutable collection frozenset features: can be repeated, the order is not rearranged