1. The principle and operation of tuples and lists

Calculate the time required to create tuples and lists ：ipython Use in timeit

1.1 The difference between tuples and lists ：

In terms of memory occupation and operation time , Tuples have more advantages than lists .

When the content does not change , Tuples are preferred ; When the content needs to change , Priority list .

1.2 Named tuples

collections Module namedtuple function

namedtuple: Receive two parameters , The name of the first type created , Second list

from collections import namedtuple
Fruits = namedtuple('Fruits', ['name', 'color', 'size'])
f = Fruits('watermelon', 'green', '3')
print(f.name)
# The output is ： watermelon

1.3 Python There are three types of data ：

• The number ：23
• Sequence ： character string , list , Tuples
• hash ： Dictionaries , aggregate

2. Principles and applications of dictionaries and collections

Dictionary derivation

The process of looking up values in dictionaries

Performance analysis ：

Compare... In terms of time ： aggregate , Dictionaries , Tuples , list

Compare from memory ： Dictionaries , aggregate , list , Tuples

3. The derived type

3.1 List derivation

Take the traversed value to the front

lis_nu = [i for i in range(1,101)]
print(lis_nu)

3.2 Dictionary derivation

dit_nu = {i: i+1 for i in range(10)}
print(dit_nu)
> {0: 1, 1: 2, 2: 3, 3: 4, 4: 5, 5: 6, 6: 7, 7: 8, 8: 9, 9: 10}

3.3 generator

3.3.1 （）

advantage ： To save memory , Improve performance

ge = (i for i in range(100))
a = next(ge)
print(a)
> 0

3.3.2 yield

yield adopt next() Value

3.4 iterator

An iterator can pass through next() Value

Iteratable object ： Sure for Loop traversal is an iterative object

Convert iteratable objects to iterators ：iter( Iteratable object )

A generator is a kind of iterator

3.4.2 send() function

def s_d():
for i in range(6):
j = yield i
print(j)
# send: Interact with the generator
dd = s_d()
print(next(dd))
print(dd.send(10))
》 The output is ：
0
10
1

send(num) function , amount to next() function , also send(num) Function passed in num The value is equal to yield i