【Python爬虫】第一周练习(二)

# -*- coding: utf-8 -*-

"""
第四次 字典 json类型 练习题
第五次 字符串分割、索引和切片练习题
第六次 逻辑运算练习题
"""

'''
第四次 字典 json类型 练习题
'''

# 导入Json
import json

# 定义一个空字典dict_a,空字典dict_b
dict_a = {}
dict_b = {}

# 给dict_a 添加3个key a1,a2,a3分别对应的值为b1,b2,b3
dict_a["a1"] = "b1"
dict_a["a2"] = "b2"
dict_a["a3"] = "b3"

# 获取dict_a所有的key,命名变量ks,打印输出ks及ks的数据类型
ks = dict_a.keys()
print("ks       ", ks)
print("type(ks) ", type(ks))

# 打印dict_a所有的value 命名变量vs,打印输出vs及vs的数据类型
vs = dict_a.values()
print("vs       ", vs)
print("type(vs) ", type(vs))

# 执行代码print(dict_a.items()) 观察输出结果
print(dict_a.items())

# 将a1和a3对应的值对换
temp = dict_a["a1"]
dict_a["a1"] = dict_a["a3"]
dict_a["a3"] = temp

# 打印输出dict_a
print(dict_a)

# 删除字典dict_a中a1对应的值
dict_a.pop("a1")

# 打印输出dict_a
print(dict_a)

# 将此时的dict_a数据更新到dict_b
dict_b.update(dict_a)

# 打印dict_b 并观察a1和a4是否在dict_b中
print(dict_b)

# a1如不存在dict_b中,输入以下代码 a1=dict_b.get('a1') 并打印变量a1
a1 = dict_b.get('a1')
print(a1)

# 将13题变量a1 添加到dict_b中,key为'a1'
dict_b["a1"] = a1

# a4如不存在dict_b中,将a4对应的值默认为'null',并添加到dict_b中,key为'a4'
a4 = 'null'
dict_b["a4"] = a4

# 打印dict_b及其数据类型
print(dict_b, type(dict_b))

# 将dict_b转化为json类型 命名为变量 json_c
json_c = json.dumps(dict_b)

# 打印json_c及其数据类型 观察16题打印结果和18题结果 将不同之处指明
print(json_c, type(json_c))

# 将json_c转换为字典类型 命名为dict_c 打印输出 dict_c及其数据类型
dict_c = json.loads(json_c)
print(dict_c, type(dict_c))

'''
第五次 字符串分割、索引和切片练习题
'''

# 理解索引这个会在之后经常用到
# 定义字符串、例如：str1 = 'http://www.jianshu.com/u/a987b338c373'字符串内容为自己的首页连接
str_1 = "https://www.jianshu.com/u/85c62640043d"

# 输出自己的id（u/之后的内容--a987b338c373）
print(str_1.split("u/")[1])

# 设s = "abcdefg"， 则下列值为
# s[3]                s[2:4]
# s[:5]               s[3:]
# s[::-1]             s[::2]
s = "abcdefg"
print(s[3], "d")
print(s[2:4], "cd")
print(s[:5], "abcde")
print(s[3:], "defg")
print(s[::-1], "gfedcba")
print(s[::2], "aceg")

# 定义列表：list1 = [1,2,3,4,5,6,7],则下列值为
# list1[3]            list1[2:4]
# list1[:5]           list1[3:]
# list1[::-1]         list1[::2]
list1 = [1, 2, 3, 4, 5, 6, 7]
print(list1[3], 4)
print(list1[2:4], [3, 4])
print(list1[:5], [1, 2, 3, 4, 5])
print(list1[3:], [4, 5, 6, 7])
print(list1[::-1], [7, 6, 5, 4, 3, 2, 1])
print(list1[::2], [1, 3, 5, 7])

# 定义元组：touple1 = (1,2,3,4,5,6,7),则下列值为
# touple1[3]          touple1[2:4]
# touple1[:5]         touple1[3:]
# touple1[::-1]       touple1[::2]
touple1 = (1, 2, 3, 4, 5, 6, 7)
print(touple1[3], 4)
print(touple1[2:4], (3, 4))
print(touple1[:5], (1, 2, 3, 4, 5))
print(touple1[3:], (4, 5, 6, 7))
print(touple1[::-1], (7, 6, 5, 4, 3, 2, 1))
print(touple1[::2], (1, 3, 5, 7))

# 对之前学习过得集中基本类型及其方法进行复习，重中之重理解索引和切片

'''
第六次 逻辑运算练习题
'''

# 下列表达式逻辑运算后的结果为?(尽量直接思考解答,可以用代码测试结果)
print("True and True", True and True, True)
print("False and True", False and True, False)
print("1 == 1 and 2 == 1", 1 == 1 and 2 == 1, False)
print("\"test\" == \"test\"", "test" == "test", True)
print("1 == 1 or 2 != 1", 1 == 1 or 2 != 1, True)
print("True and 1 == 1", True and 1 == 1, True)
print("False and 0 != 0", False and 0 != 0, False)
print("True or 1 == 1", True or 1 == 1, True)
print("\"test\" == \"testing\"", "test" == "testing", False)
print("1 != 0 and 2 == 1", 1 != 0 and 2 == 1, False)
print("\"test\" != \"testing\"", "test" != "testing", True)
print("\"test\" == 1", "test" != "testing", True)
print("not (True and False)", not (True and False), True)
print("not (1 == 1 and 0 != 1)", not (1 == 1 and 0 != 1), False)
print("not (10 == 1 or 1000 == 1000)", not (10 == 1 or 1000 == 1000), False)
print("not (1 != 10 or 3 == 4)", not (1 != 10 or 3 == 4), True)
print("not (\"testing\" == \"testing\" and \"Zed\" == \"Cool Guy\")",
      not ("testing" == "testing" and "Zed" == "Cool Guy"), True)
print("1 == 1 and not (\"testing\" == 1 or 1 == 0)", 1 == 1 and not ("testing" == 1 or 1 == 0), True)
print("3 == 3 and not (\"testing\" == \"testing\" or \"Python\" == \"Fun\")",
      3 == 3 and not ("testing" == "testing" or "Python" == "Fun"), False)