dictionary
One of the basic data types, {} stores data in the form of key-value pairs.
***
A large amount of relational data is mapped and stored in the form of key:value.
The key of the dictionary, which must be an immutable data type, is unique.
The value of the dictionary can be any data type.
***
Dictionaries are unordered until python3.5 (including 3.5).
But it is ordered after python3.6.
The query speed of the dictionary is very fast, and it stores a large amount of relational data.
How to query the dictionary:
Through the hash algorithm, the keys of the dictionary are converted into numbers through the hash table, and the binary search is used to query the numbers.
***
Classification of data types:
mutable (unhashable): list, dict, set,
immutable (hashable): str, tuple, int, bool
***
Containers (3 types)
list，dict，tuple，
Non-container (3 types)
int，bool，set
***
Dictionary: (Add, delete, modify, search)
increase:
dic = { ' name ' : ' old boy ' , ' age ' : 56, ' hobby ' : ' women ' ,}
dic[ ' name ' ] = ' hahah ' #Responsible to replace, not responsible to add.
print (dic)
answer:
{'age': 56, 'hobby': 'women', 'name': 'hahah' }
dic['aaa'] = 'ccc' #Add to the end by default
print(dic)