dict() constructor builds dictionaries directly from sequences of key-value pairs, or can be used to create dictionaries from arbitrary key and value expressions; sometimes, when the keys are simple strings, it's easier to specify pairs using keyword arguments:
A dict literal is created by surrounding a key-value list with{}'s; a keys is separated from its value with:'s, and thekey:valuepairs are separated with commas (,). An emptydictis simply{}.
Examples:
? ? ? ? ? ? ? ? ?dict_li = {"name": "Danniel", "class": "class 1", "age": 6, "boy": "yes"}
? ? ? ? ? ? ? ? ? dict_li2 = {(6,6): "blue pair", (2,5,3): " red traingle", "pentagon":["white","big,"building"]}
? ? ? ? ? ? ? ? ? dict_li3 = {}
#1. the difference between dict literal and dict() constructor:
1). dict literal, key-value paries: ??
def literal():
? ? ? ? ? ? ? ? ?d = {'first': 1, 'second': 2}
def constructor():
? ? ? ? ? ? ? ? ?d = dict(first = '1', second='2')
Using dis module to analyze the implementation details of CPython interpreter:
literal is little bit faster, cause it uses optimized BUILD_MAP and STORE_MAP opcodes rather than generic CALL_FUNCTION.
Example of dict() usage: dict.items(), dict.get(key, 0), dict.keys(), dict.values()
