Python Learning: Dictionaries

Dictionary

1. Querying memory Addresses

A = 10

Print (ID (a))

b = A

Print (ID (b))

b = 15

Print (ID (b))

2. Data type

Immutable types: Integer, string, tuple

Mutable type: list, dictionary

The value of a dictionary can be any type, and the key can only be an immutable type.

The dictionary store is unordered. For example:

DIC = {' name ': ' YSW ', ' age ': $, ' hobby ': ' Game ', ' Is_handsome ': True}

Print (DIC)

Print (dic[' name '])

#dic = {1: ' ysw ', ' age ': $, ' hobby ': ' Game ', ' Is_handsome ': True}

#print (DIC)

#print (Dic[1])

#dic = {[up]: ' YSW ', ' age ': $, ' hobby ': ' Game ', ' Is_handsome ': True}

#print (DIC)

#print (dic[[1,2]])

#dic = {' name ': ' YSW ', ' age ': $, ' hobby ': {' game_name ': ' wow ', ' level ': ' + '}, ' Is_handsome ': True}

#print (dic[' hobby ')

#dic = {' 1 ': ' 123 '}, ' age ': $, ' hobby ': {' game_name ': ' wow ', ' level ': ' + '}, ' Is_handsome ': True}

#print (DIC)

#字典两大特点: unordered; key unique

#dic = {' age ': ' YSW ', ' age ': $, ' hobby ': ' Game ', ' Is_handsome ': True}

#print (DIC)

3. Two ways to create a dictionary:

#dic1 = {' name ': ' YSW '}

#dic2 = Dict ((' Name ', ' YSW '),)

4. Corresponding operation

(1) Increase

Dic1 = {' name ': ' YSW '}

Dic1[' age '] = 18

Print (DIC1)

dic1[' name '] = 18

Print (DIC1)

#没有重复的键就添加, replace the value with a duplicate key

------------------------------

Dic1 = {' name ': ' YSW '}

Dic1[' age '] = 18

Print (DIC1)

Dic1.setdefault (' age ', 36)

Print (DIC1)

#dic1. SetDefault (' hobby ', ' game ')

#print (DIC1)

#setdefault的特点: No duplicate keys are added, there is no change to duplicate keys

Python Learning: Dictionaries