Summary of the second week

Summary of the second week

1. Installation environment

  • Download requests pip package

    Modify the download source of the third-party library to the domestic mirror website ---> pip config set global.index-url https://pypi.doubanio.com/simple
 Third party Library ---> requests ---> pip install requests

agreement ---> The rules of conversation to be observed by both sides of communication.

HTTP / HTTPS ---> adopt URL Protocol for accessing network resources ---> Hyper-Text Transfer Protocol(Hypertext Transfer Protocol)

Request( request) - Respond( response)

2. Knowledge summary

1. List

  • 1. Three ways to build lists

    list1=['a','b','c']
# Method 1 of creating list: literal syntax

list2=list(range(1,10))
# Create list method 2: constructor method

list3=[i** 2for i in range(1,10)]
# Create list method 3, generative (deductive) syntax

  • 2. List function, traversal index, member operation, merging, ratio size (according to the first number, letter, Chinese character, according to Kangxi dictionary)

    for i ,x in enumerate(list1):
    print(i,x)
# Traversal, you can add labels

print(10 in list3)
print(5 not in list2)
# Member operation


list5=[1,3,5,7]
list6=[4,4,8]
list6+=list5
print(list6)
# merge

list7= list(range(1,8,2))
list8=[0,3,5,7,9]
print(list7>list8)
# Than the size than the first number

list9 =['apply']
list10 =['black']
print(list9>list10)
# According to the coding ratio of letters

print('Da Chui Wang'<'You Duanwei')
# Kangxi dictionary

  • 3. List operation, add (two), delete (three), find the display position, calculate the number, reverse the list, and sort the list. If
    The elements in the list are in string form and can be converted to integers

    nums =[0,10,100,1000]

nums.append(10000)
# Add a data at the end
nums.insert(1,5)
# Adds an element at the specified location

nums.pop()
# Delete the last element
nums.pop(0)
# Deletes the element at the specified location
del nums[0]
# Delete the element at the specified location, which is not commonly used

nums.remove(1000)
# If there are more than 1000 Remove first
while 1000 in nums:
    nums.remove(1000)
# Delete all 1000

if 1000 in nums:
    print(nums.index(1000))
# Displays the location of 1000

if 1000 in nums:
    print(nums.count(1000))
# Count 1000

nums.reverse()
# Reverse operation

nums.sort()
# Sorting: ascending by default, from small to large. (reverse=True) can be changed to descending order.

nums.sort(key=int)
# Convert the elements of the list to integer sort

  • 4. Sampling in the list, 3 kinds of sampling and 1 kind of disorder

    import random
nums =[1,2,3,4,5,6,7,8,9,10]
print(random.sample(nums,k=5))
# Sampling without return
print(random.choices(nums,k=5))
# Yes, put it back for sampling
print(random.choice(nums))
# Select one at random
random.shuffle(nums)
print(nums)
# Reorder

2. Tuple

  • 1. Repeat operation, member operation, merge operation, index slice (tuple is an immutable container, which is the same as list except that it cannot be changed)

    a=(0,)
b=(1,2,4)
# Tuples are immutable containers
print(type(a))

print(a*3)
# Repeat operation

print(3 in b)
print(2 not in b)
# Member operation

c=a+b
print(c)
# Merge operation

print(a[0],b[1:3])
# Index slice

# However, it cannot be modified (added or deleted)

3. String

  • 1. There are three ways to build strings

    a='hello'
b ="hello"
c="""
hello
"""
print(a,b,c)
# There are three ways to enter a string

  • 2. String tab, line break, placeholder, escape

    s1 = '\time up \now'
print(s1)
# In string s1, \ tis a tab character (four spaces), \ NIS a newline character
s2 = r'\time up \now'
print(s2)
# String with placeholder, keep the original meaning

s3 = '\141\142\143\x61\x62\x63'
print(s3)
s4 ='\u9a86 \u660a'
print(s4)
# \u. Escape to Chinese

  • 3. For string operation, note: string is also a constant data type, and can only be read, not rewritten!!! Gets the length of the string (the string has no subscript, which is the same as the collection). Loop traversal, repetition, member operation, comparison size (character encoding size), string splicing.

    a = 'hello, world'

# Gets the length of the string
print(len(a))

# TypeError: 'str' object does not support item assignment
# a[0] = 'H'

# Loop through each character of the string
for i in range(len(a)):
    print(a[i])

for i in a:
    print(i)

# repeat
print(a * 5)
# Member operation
print('or' in a)
print('ko' in a)

b = 'hello, World'
# Comparison operation (compare the contents of string -- > character encoding size)
print(a == b)
print(a != b)

c = 'goodbye, world'
print(b > c)

d = 'hello, everybody'
print(b >= d)

print(ord('W'), ord('e'))

# String splicing
e = '!!!'
print(d + e)

f = ' goodbye'
print(d + e + f)

  • 4. String transformation, four kinds of conversion to case, four kinds of judgment, head and tail judgment

    a = 'i LOVE you'

# Capitalize
print(a.upper())
# Turn lowercase
print(a.lower())
# title case
print(a.capitalize())
# Capitalize each word
print(a.title())

b = 'abc123'
# Determine whether the string is a number
print(b.isdigit())
# Determine whether the string is a letter
print(b.isalpha())
# Determine whether the string is a letter or a number
print(b.isalnum())
# Determine whether the string is an ASCII character
# A method added in Python 3.7
print(b.isascii())

c = 'How do you do'
print(c.isascii())

# Determines whether the string starts with the specified content
print(c.startswith('Hello'))
# Determines whether the string ends with the specified content
print(c.endswith('ah'))

  • 5. Find the word position specified in the string (two types)

    a = 'Oh apple, i love apple.'
# index - find the specified substring from left to right. You can specify where to start. The default is 0
# The index (subscript) corresponding to the returned substring is found, and a direct error is reported if it is not found (program crash)
print(a.index('apple'))
print(a.index('apple', 10))
print(a.rindex('apple'))

# ValueError: substring not found
# print(a.index('banana'))

print(a.find('apple'))
print(a.find('apple', 10))
print(a.rfind('apple'))
print(a.find('banana'))
print(a.rfind('banana'))

  • 6. String, right justified, left justified

    print(a.center(30,' '))
# The center method centers the string with a width of 80
print(a.rjust(60,'*'))
# The rjust method aligns the string to the right with a width of 60
print(a.ljust(20,'-'))
# The ljust method aligns the string to the left with a width of 20

  • 7. Extra space in string

    s = '   jackfrued@126.com  \t\r\n'
# The strip method obtains the string after trimming the left and right spaces of the string
print(s)
print(s.strip())    # jackfrued@126.com

  • 8. Replace the specified character in the string with the specified character

    a='hello,world'
a_1=a.replace(',',' ')
# Convert, to spaces

  • 9. Splitting and merging of strings

    words =a_1.split()
print(words,len(words))
# You can split it at will

words=a_1.rsplit()
print(words,len(words))
# Split from left to right

words=a_1.split(' ',maxsplit=1)   
# It can be split at most once


c=['abc','def','ghi']
print('-'.join(c))
# Merge strings in the list

  • 10. Computer coding into language

    a='I love you China'
b=a.encode('gbk')
c=a.encode('utf-8')
# GBK < ----- GB2312 (two English words are combined into one Chinese) ---- ascii (English) (so Chinese is 2 bytes and English is 1 byte)
# utf-8 coding is an implementation of unicode (universal code). Chinese characters are 3 bytes in utf-8
print(type(b))
print(b)
print(c)
d=b'\xce\xd2\xb0\xae\xc4\xe3\xd6\xd0\xb9\xfa'
e=b'\xe6\x88\x91\xe7\x88\xb1\xe4\xbd\xa0\xe4\xb8\xad\xe5\x9b\xbd'
print(d.decode('gbk'),len(d))
print(e.decode('utf-8'),len(e))

# uft-8 is a variable length byte
# Numbers and English are one byte
# Chinese is three bytes
# The expression enmoj is four characters

  • 11. String clear code and secret code conversion

    message ='i love you'
table =str.maketrans('abcdefghijklmnopqrstuvwxyz','defghijklmnopqrstuvwxyzabc')
# String conversion is realized through the translate method of string
print((message.translate((table))))

4. Assembly

  • 1. Create an empty collection

    set2 = set()
print(set2)
# Create an empty collection

  • 2. Three characteristics of sets, certainty, mutual anisotropy and disorder

    set1 = {1,2,1,2,3,3,4,6}
print(type(set1))
print(set1)
# Mutual anisotropy, output can only be 1, 2, 3, 4, 6

# print(set[1])
# # Disorder, error will be reported

  • 3. Intersection, union, difference set and symmetric difference of sets

    set1 = {1, 2, 3, 4, 5}
set2 = {2, 4, 6, 8}

# Member operation - deterministic (elements are either in or out of the set)
# The efficiency of member operation of set is much higher than that of list
print(1 in set1)
print(1 not in set1)

# intersection
print(set1 & set2)
print(set1.intersection(set2))
# Union
print(set1 | set2)
print(set1.union(set2))
# Difference set
print(set1 - set2)
print(set1.difference(set2))
print(set2 - set1)
print(set2.difference(set1))
# Symmetry difference
print(set1 ^ set2)
print((set1 | set2) - (set1 & set2))
print(set1.symmetric_difference(set2))

  • 4. Set judgment, true subset, subset, superset

    set3 = {1, 2, 3, 4, 5, 6, 7, 8, 9}
# Judge true subset
print(set1 < set3)
print(set1.issubset(set3))
# Judgment subset
print(set1 <= set3)
# Judgment superset
print(set3 > set2)
print(set3.issuperset(set2))

  • 5. Add elements to the collection, delete elements, and empty elements

    # Hash storage is used at the bottom of the collection
# The key of hash storage is to design a good hash function to make different objects produce different hash codes as much as possible
# Immutable containers cannot be put into the collection, and hash codes cannot be calculated. As a collection element
# Hash storage is used at the bottom of the collection. The location of element storage is determined by calculating the hash code of the element, which is an efficient storage scheme.
# The key of hash storage is to design a good hash function to ensure that different objects can calculate different hash codes.
# Variable containers (list, set, dictionary) cannot calculate hash codes, so they cannot be put into the set as elements of the set
set1 = {'apple', 'banana', 'pitaya', 'apple'}

# Add element
set1.add('grape')
set1.add('durian')
print(set1)

# Delete element
set1.discard('pitaya')
print(set1.pop())
print(set1.pop())
print(set1)

# Empty element
set1.clear()
print(set1)

5. Dictionary

  • 1. Three ways to build a dictionary

    student1={'id':'56466',
          'name':'ydw',
          'sex':'true',
          'birthday':'1980-11'
          }
print(student1)

student2=dict(id=1002,name='ydx',sex=True)
print(student2)
# Constructor function

dict1 = {i:i**2 for i in range(1,10)}
print(dict1)
# Generative grammar

  • 2... Traverse the keys in the dictionary, the values in the dictionary, and the key value pairs in the dictionary

    for key in student1.keys():
    print(key)
# Traverse keys in the dictionary
print('-'*20)

for value in student1.values():
    print(value)
print('-'*20)
# Traverse the values in the dictionary

for key,value in student1.items():
    print(key,value)
# Traverse key value pairs

  • 3. Member operation and dictionary index (one can add key value pairs and the other will report errors). Dictionary addition and deletion of key value pairs.

    student1['address']='Chengdu, Sichuan'
print(student1)
# How to add a set of key value pairs if there is no corresponding index in the dictionary

print(student1.get('age'))
print(student1.get('age',20))
print(student1['birthday'])
# If you use get, no error will be reported. If not, a null value will be returned (you can specify the default value)
del student1['name']
# Delete key value pair
# It's best to use get, or judge whether this key exists before outputting

  • 4. Update the merge dictionary, delete key value pairs, and find replacement key value pairs

    dict1 = {'A': 100, 'B': 200, 'C': 300}
dict2 = {'D': 400, 'E': 500, 'A': 600}

# Update (merge or update of elements)
dict1.update(dict2)
print(dict1)
print('-'*20)

# The delete -- > key must exist. If it does not exist, KeyError will be generated
# del dict1['B']
dict1.pop('B')
dict1.popitem()
# The last key value pair is deleted by default
print(dict1)
print('-'*20)

print(dict1.setdefault('C'))
print(dict1.setdefault('K', 10000))
# If the key does not exist in the dictionary, the key will be added and the default value will be set as the default value of the key. If the key exists in the dictionary, the original corresponding value of the key will be read out
# , the value of default will not overwrite the existing one
print(dict1)

# Empty all
dict1.clear()
print(dict1)

  • 5. Through the interface, jason can convert the online data dictionary into our available data

    """
example08 - Network access JSON Format data and parse out the required content

Modify the download source of the third-party library to the domestic mirror website ---> pip config set global.index-url https://pypi.doubanio.com/simple
 Third party Library ---> requests ---> pip install requests

agreement ---> The rules of conversation to be observed by both sides of communication.

HTTP / HTTPS ---> adopt URL Protocol for accessing network resources ---> Hyper-Text Transfer Protocol(Hypertext Transfer Protocol)

Request( request) - Respond( response)

Author: Hao
Date: 2021/7/30
"""
import requests

# Initiate a request through the get function and get a response
resp = requests.get(
    url='http://api.tianapi.com/guonei/index',
    params={'key': 'e8c5524dd2a365f20908ced735f8e480', 'num': 30}
)
# news_dict = json.loads(resp.text)
# Get JSON data from the response and directly convert it into a dictionary
news_dict = resp.json()
news_list = news_dict['newslist']
for news in news_list:
    print(news['title'])
    print(news['url'])

Keywords: Python

Added by sebastiaandraaisma on Tue, 04 Jan 2022 09:51:34 +0200

Popular Keywords

©2025 Programming VIP