Python数据分析_第01课：Python概览_笔记

秒速五厘米 2021-11-02 11:08 407阅读 0赞

### 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][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)

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

[https_github.com_RealEmperor_Python-for-Data-Analysis]: https://github.com/RealEmperor/Python-for-Data-Analysis