Python数据分析_第01课:Python概览_笔记变量类型运算符

文章目录

  • 变量类型

    • 打印

    • 行和缩进

    • 多行语句

    • 引号

    • 注释

    • 空行

    • 码组

    • 帮助

    • 变量赋值

    • 数字

    • 删除

    • 字符串

    • 列表

    • 元组

    • 字典

  • 运算符

    • 比较运算符

    • 赋值运算符

    • 位运算符

    • 逻辑运算符

    • 成员运算符

    • 身份运算符

    • 运算符优先级

GitHub: https://github.com/RealEmperor/Python-for-Data-Analysis

变量类型

打印

    # 打印
  print("Hello, Python!")
    Hello, Python!

行和缩进

    # 行和缩进
  if True:
      print("True")
  else:
      print("False")
    True
    if True:
      print("Answer")
      print("True")
  else:
      print("Answer")
      # 没有严格缩进,在执行时报错
        print("False")
      File "<ipython-input-3-d9287ace04e4>", line 7
      print("False")
      ^
  IndentationError: unexpected indent

多行语句

    # 多行语句
  item_one = 1
  item_two = 2
  item_three = 3
  total = item_one + \
          item_two + \
          item_three
  print(total)
    6
    days = ['Monday', 'Tuesday', 'Wednesday',
            'Thursday', 'Friday']
    days
    ['Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday']

引号

    # 引号
    word = 'word'
    sentence = "这是一个句子。"
    paragraph = """这是一个段落。
    包含了多个语句"""
    print(word)
    print(sentence)
    print(paragraph)
    word
    这是一个句子。
    这是一个段落。
    包含了多个语句

注释

    # 注释
    # 第一个注释
    print("Hello, Python!")  # 第二个注释
    name = "Madisetti"  # 这是一个注释
    
    '''
    这是多行注释,使用单引号。
    这是多行注释,使用单引号。
    这是多行注释,使用单引号。
    '''
    
    """
    这是多行注释,使用双引号。
    这是多行注释,使用双引号。
    这是多行注释,使用双引号。
    """

空行

    # 空行
    eval(input("\n\nPress the enter key to exit."))
    import sys
    
    x = 'foo'
    sys.stdout.write(x + '\n')
    foo

码组

    # 码组
    '''
    if expression : 
       suite 
    elif expression :  
       suite  
    else :  
       suite 
    '''

帮助

    # 帮助
    help(sys.stdout.write)
    Help on method write in module ipykernel.iostream:
    
    write(string) method of ipykernel.iostream.OutStream instance
        Write string to stream.
        Returns the number of characters written (which is always equal to
        the length of the string).

变量赋值

    # 变量赋值
    counter = 100  # 赋值整型变量
    miles = 1000.0  # 浮点型
    name = "John"  # 字符串
    
    print(counter)
    print(miles)
    print(name)
    
    a = b = c = 1
    print(a, b, c)
    a, b, c = 1, 2, "john"
    print(a, b, c)
    100
    1000.0
    John
    1 1 1
    1 2 john

数字

    # 数字
    var1 = 1
    var2 = 10

删除

    #  删除 del var1[,var2[,var3[....,varN]]]]
    var = 5896419821
    var_a = 0.22
    var_b = 3e2
    del var
    del var_a, var_b

字符串

    # 字符串
    # s="a1a2•••an"(n>=0)
    s = 'ilovepython'
    print((s[1:5]))
    print((s[5:-1]))
    
    str = 'Hello World!'
    print(str)  # 输出完整字符串
    print(str[0])  # 输出字符串中的第一个字符
    print(str[2:5])  # 输出字符串中第三个至第五个之间的字符串
    print(str[2:])  # 输出从第三个字符开始的字符串
    print(str * 2)  # 输出字符串两次
    print(str + "TEST")  # 输出连接的字符串
    love
    pytho
    Hello World!
    H
    llo
    llo World!
    Hello World!Hello World!
    Hello World!TEST

列表

    # 列表
    list = ['abcd', 786, 2.23, 'john', 70.2]
    tinylist = [123, 'john']
    
    print(list)  # 输出完整列表
    print(list[0])  # 输出列表的第一个元素
    print(list[1:3])  # 输出第二个至第三个的元素 
    print(list[2:])  # 输出从第三个开始至列表末尾的所有元素
    print(tinylist * 2)  # 输出列表两次
    print(list + tinylist)  # 打印组合的列表
    ['abcd', 786, 2.23, 'john', 70.2]
    abcd
    [786, 2.23]
    [2.23, 'john', 70.2]
    [123, 'john', 123, 'john']
    ['abcd', 786, 2.23, 'john', 70.2, 123, 'john']

元组

    # 元组
    tuple = ('abcd', 786, 2.23, 'john', 70.2)
    tinytuple = (123, 'john')
    
    print(tuple)  # 输出完整元组
    print(tuple[0])  # 输出元组的第一个元素
    print(tuple[1:3])  # 输出第二个至第三个的元素 
    print(tuple[2:])  # 输出从第三个开始至列表末尾的所有元素
    print(tinytuple * 2)  # 输出元组两次
    print(tuple + tinytuple)  # 打印组合的元组
    
    tuple = ('abcd', 786, 2.23, 'john', 70.2)
    list = ['abcd', 786, 2.23, 'john', 70.2]
    tuple[2] = 1000  # 元组中是非法应用
    list[2] = 1000  # 列表中是合法应用
    ('abcd', 786, 2.23, 'john', 70.2)
    abcd
    (786, 2.23)
    (2.23, 'john', 70.2)
    (123, 'john', 123, 'john')
    ('abcd', 786, 2.23, 'john', 70.2, 123, 'john')
    
    
    
    ---------------------------------------------------------------------------
    
    TypeError                                 Traceback (most recent call last)
    
    <ipython-input-17-db0548b12b81> in <module>()
         12 tuple = ('abcd', 786, 2.23, 'john', 70.2)
         13 list = ['abcd', 786, 2.23, 'john', 70.2]
    ---> 14 tuple[2] = 1000  # 元组中是非法应用
         15 list[2] = 1000  # 列表中是合法应用
    
    
    TypeError: 'tuple' object does not support item assignment

字典

    # 字典
    dict = {}
    dict['one'] = "This is one"
    dict[2] = "This is two"
    
    tinydict = {'name': 'john', 'code': 6734, 'dept': 'sales'}
    
    print(dict['one'])  # 输出键为'one' 的值
    print(dict[2])  # 输出键为 2 的值
    print(tinydict)  # 输出完整的字典
    print(list(tinydict.keys()))  # 输出所有键
    print(list(tinydict.values()))  # 输出所有值

运算符

算术运算符

    # 算术运算符
    a = 21
    b = 10
    c = 0
    
    c = a + b
    print("Line 1 - Value of c is ", c)
    
    c = a - b
    print("Line 2 - Value of c is ", c)
    
    c = a * b
    print("Line 3 - Value of c is ", c)
    
    c = a / b
    print("Line 4 - Value of c is ", c)
    
    c = a % b
    print("Line 5 - Value of c is ", c)
    
    a = 2
    b = 3
    c = a ** b
    print("Line 6 - Value of c is ", c)
    
    a = 10
    b = 5
    c = a // b
    print("Line 7 - Value of c is ", c)
    Line 1 - Value of c is  31
    Line 2 - Value of c is  11
    Line 3 - Value of c is  210
    Line 4 - Value of c is  2.1
    Line 5 - Value of c is  1
    Line 6 - Value of c is  8
    Line 7 - Value of c is  2

比较运算符

    # 比较运算符
    a = 21
    b = 10
    c = 0
    
    if (a == b):
        print("Line 1 - a is equal to b")
    else:
        print("Line 1 - a is not equal to b")
    
    if (a != b):
        print("Line 2 - a is not equal to b")
    else:
        print("Line 2 - a is equal to b")
    
    if (a != b):
        print("Line 3 - a is not equal to b")
    else:
        print("Line 3 - a is equal to b")
    
    if (a < b):
        print("Line 4 - a is less than b")
    else:
        print("Line 4 - a is not less than b")
    
    if (a > b):
        print("Line 5 - a is greater than b")
    else:
        print("Line 5 - a is not greater than b")
    
    a = 5
    b = 20
    if (a <= b):
        print("Line 6 - a is either less than or equal to  b")
    else:
        print("Line 6 - a is neither less than nor equal to  b")
    
    if (b >= a):
        print("Line 7 - b is either greater than  or equal to b")
    else:
        print("Line 7 - b is neither greater than  nor equal to b")
    Line 1 - a is not equal to b
    Line 2 - a is not equal to b
    Line 3 - a is not equal to b
    Line 4 - a is not less than b
    Line 5 - a is greater than b
    Line 6 - a is either less than or equal to  b
    Line 7 - b is either greater than  or equal to b

赋值运算符

    # 赋值运算符
    a = 21
    b = 10
    c = 0
    
    c = a + b
    print("Line 1 - Value of c is ", c)
    
    c += a
    print("Line 2 - Value of c is ", c)
    
    c *= a
    print("Line 3 - Value of c is ", c)
    
    c /= a
    print("Line 4 - Value of c is ", c)
    
    c = 2
    c %= a
    print("Line 5 - Value of c is ", c)
    
    c **= a
    print("Line 6 - Value of c is ", c)
    
    c //= a
    print("Line 7 - Value of c is ", c)
    Line 1 - Value of c is  31
    Line 2 - Value of c is  52
    Line 3 - Value of c is  1092
    Line 4 - Value of c is  52.0
    Line 5 - Value of c is  2
    Line 6 - Value of c is  2097152
    Line 7 - Value of c is  99864

位运算符

    # 位运算符
    a = 60  # 60 = 0011 1100 
    b = 13  # 13 = 0000 1101 
    c = 0
    
    c = a & b  # 12 = 0000 1100
    print("Line 1 - Value of c is ", c)
    
    c = a | b  # 61 = 0011 1101 
    print("Line 2 - Value of c is ", c)
    
    c = a ^ b  # 49 = 0011 0001
    print("Line 3 - Value of c is ", c)
    
    c = ~a  # -61 = 1100 0011
    print("Line 4 - Value of c is ", c)
    
    c = a << 2  # 240 = 1111 0000
    print("Line 5 - Value of c is ", c)
    
    c = a >> 2  # 15 = 0000 1111
    print("Line 6 - Value of c is ", c)
    Line 1 - Value of c is  12
    Line 2 - Value of c is  61
    Line 3 - Value of c is  49
    Line 4 - Value of c is  -61
    Line 5 - Value of c is  240
    Line 6 - Value of c is  15

逻辑运算符

    # 逻辑运算符
    a = 10
    b = 20
    c = 0
    
    if (a and b):
        print("Line 1 - a and b are true")
    else:
        print("Line 1 - Either a is not true or b is not true")
    
    if (a or b):
        print("Line 2 - Either a is true or b is true or both are true")
    else:
        print("Line 2 - Neither a is true nor b is true")
    
    a = 0
    if (a and b):
        print("Line 3 - a and b are true")
    else:
        print("Line 3 - Either a is not true or b is not true")
    
    if (a or b):
        print("Line 4 - Either a is true or b is true or both are true")
    else:
        print("Line 4 - Neither a is true nor b is true")
    
    if not (a and b):
        print("Line 5 - Either a is not true or b is  not true or both are not true")
    else:
        print("Line 5 - a and b are true")
    Line 1 - a and b are true
    Line 2 - Either a is true or b is true or both are true
    Line 3 - Either a is not true or b is not true
    Line 4 - Either a is true or b is true or both are true
    Line 5 - Either a is not true or b is  not true or both are not true

成员运算符

    # 成员运算符
    a = 10
    b = 20
    list = [1, 2, 3, 4, 5]
    
    if (a in list):
        print("Line 1 - a is available in the given list")
    else:
        print("Line 1 - a is not available in the given list")
    
    if (b not in list):
        print("Line 2 - b is not available in the given list")
    else:
        print("Line 2 - b is available in the given list")
    
    a = 2
    if (a in list):
        print("Line 3 - a is available in the given list")
    else:
        print("Line 3 - a is not available in the given list")
    Line 1 - a is not available in the given list
    Line 2 - b is not available in the given list
    Line 3 - a is available in the given list

身份运算符

    # 身份运算符
    a = 20
    b = 20
    
    if (a is b):
        print("Line 1 - a and b have same identity")
    else:
        print("Line 1 - a and b do not have same identity")
    
    if (id(a) == id(b)):
        print("Line 2 - a and b have same identity")
    else:
        print("Line 2 - a and b do not have same identity")
    
    b = 30
    if (a is b):
        print("Line 3 - a and b have same identity")
    else:
        print("Line 3 - a and b do not have same identity")
    
    if (a is not b):
        print("Line 4 - a and b do not have same identity")
    else:
        print("Line 4 - a and b have same identity")
    Line 1 - a and b have same identity
    Line 2 - a and b have same identity
    Line 3 - a and b do not have same identity
    Line 4 - a and b do not have same identity

运算符优先级

    # 运算符优先级
    a = 20
    b = 10
    c = 15
    d = 5
    e = 0
    
    e = (a + b) * c / d  # ( 30 * 15 ) / 5
    print("Value of (a + b) * c / d is ", e)
    
    e = ((a + b) * c) / d  # (30 * 15 ) / 5
    print("Value of ((a + b) * c) / d is ", e)
    
    e = (a + b) * (c / d)  # (30) * (15/5)
    print("Value of (a + b) * (c / d) is ", e)
    
    e = a + (b * c) / d  # 20 + (150/5)
    print("Value of a + (b * c) / d is ", e)
    Value of (a + b) * c / d is  90.0
    Value of ((a + b) * c) / d is  90.0
    Value of (a + b) * (c / d) is  90.0
    Value of a + (b * c) / d is  50.0

参考资料:炼数成金Python数据分析课程

 

posted on 2021-07-01 21:08  BabyGo000  阅读(75)  评论(0)    收藏  举报