I believe there was a foundation python Students with job interview experience , Must have been asked about the list 、 Knowledge of dictionaries and tuples . The most frequently asked questions are those commonly used in these three data structures API, Or give you some questions on the spot , Through these data structures coding Realization , There are many network resources for these contents , I won't introduce them here . This article mainly explains the main differences between the three and the nine key points of mastering them ！

list

• 1. Different types of objects can be stored in the list

L = [1,'a',1.234,[1,2,3],(4,5,6)]

print(L)

Output

[1, 'a', 1.234, [1, 2, 3], (4, 5, 6)]

• 2. A list is an ordered queue , You can get a single element by position sequence number

L = [1,'a',1.234,[1,2,3],(4,5,6)]

print(L[3])

Output

[1, 2, 3]

• 3. The list has unlimited length , That's not enough

Tuples

• 4. Tuples can be thought of as immutable lists , Tuples use braces ( ), Use square brackets for lists [ ].

Changing the values of a list is easy

L1=[1,2,3]

L1[1]=10

print(L1)

Output

[1, 10, 3]

When we try to change the value in a tuple

L2=('a','b','c')

L2[1]='x'

print(L2)

Output error prompt

L2[1]='x'

TypeError: 'tuple' object does not support item assignment

• 5. So you might ask , Why design tuples ？ It's simple , Tuples occupy less memory resources than lists ！

Dictionaries

• 6. A dictionary is a hash table , The objects in the dictionary are out of order .
• 7. Dictionaries reflect a mapping relationship through pairs of key values .
• 8. Every key in the dictionary is unique .

dic={'name':'kevin','age':40}

print(dic)

Output the whole dictionary {'name':'kevin','age':40}

print(dic['name'])

Output key by name Value ： 'kevin'

print(dic.values())

Output all values of the dictionary ['kevin',40]

print(dic.keys())

Output all the keys of the dictionary ['name','age']

• 9. You may ask again , Why design a dictionary ？ It's simple , When a large amount of data processing is involved , Dictionaries are much more efficient than lists ！