---

title: "An R Markdown document converted from "01.ipynb""

一、“单值”——标量类型

1.标量类型

1.1 整数类型int

a = 1

type(a)

1.2 浮点数值float

b = 11.0

type(b)

1.3 字符串类型str

c = "3"

type(c)

d =" python"

d = "python"

type(d)

'python'

type('python')

1.4 布尔值类型bool

b

a

a == b

a > 0

type(a > 0)

1.5 空值NoneType

e = None

type(e)

2.标量之间的互相转换

a = 2

type(a)

b = str(a)

b

type(b)

c = int(b)

c

type(c)

type(2.5)

int(2.5)

c="d"

int(c)

3.标量的运算

a = 3
b = 2

a + b

a / b

a // 4

a = "3"
b = "2"

c=a + b

c

int(c)

小结：

1.标量类型：int/float/str/bool/NoneType

2.标量之间的互相转换

3.标量的运算

二、数据结构

1.常见数据结构

1.1 元组,tuple()

a = (1, "2", 3)

type(a)

a[0]

type(a[1])

b =((1, 2, 3),(4, 5))

b[0]

1.2 列表,list[]

c = [1, 2 ,3]

type(c)

d = [(1,2,3),"python", 4, None]

d[0]

type(d[0])

type(d[2])

type(d[3])

1.3 字典,dict{}, keys-values, 键值对

d = {'a' : 'some value', 'b' : [1, 2, 3, 4]}

type(d)

d.keys()

d.keys()

d.values()

e = [1, 2, 3, "python", (4, 5)]

f = [6, 7, 8 ,9, 10, 11]

zip(e,f)

g = dict(zip(e,f))
g

h = list(zip(e,f))
h

zip(e,f)

1.4 集合,set{}

a = {1, 2, 3,4,4}

a

type(a)

b = {1, 2, 2, 3, 3,}

b

a == b

2.数据结构之间的互相转换

a = (1, 2, 3)

b = list(a)

b

c = tuple(b)

c

a == c

c = ((1, 2), (3, 4), (5, 6))

d = list(c)

d

e = dict(c)

e

f = dict(d)

f

d = list(f)

d

e = tuple(f)

e

d_ = list(f.values())

d_

小结：

一、单值——标量类型

1.标量类型：int/float/str/bool/None

2.标量之间的互相转换

3.标量的运算

二、数据结构

1.常见数据结构：tuple/list/dict/set

2.数据结构之间的互相转换

三、列表

1.列表list的运算

a = [1, 2 ,3]
b = [4, 5, 6]

a+b 

a = (1, 2 ,3)
b = (4, 5, 6)

a + b 

2.列表list的索引

a = [1, 2, 3, 4, (5, 6)]

a[0]

a[0] = "p"

a

a.append((7,8,9))

a

a[4]

a[5] = 5.5

a

a[-1]

a.append(9)

a

b = ([1, 2, 3], 4, 5)

b=list(b)

b.append(6)

b[0]

b[0].append(6)

b

3.列表list的方法及常用函数（删除，合并）

a = [2, 1, 3, 4, 5]

a.pop(4)

a

a.append("10 决策树.ipynb")

a

a.insert(1,5)

a

a.pop(-1)

a

sorted(a)

b = sorted(a)

b

a

c = list(reversed(a))

c

reversed(a)

四、函数

1.内置函数

a = [2, 1, 3, 4]
b = [5, 6, 7, 8]

sorted(a)

a

reversed(a)

zip(a,b)

list(zip(a,b))

2.自定义函数def

def qua(x, y):
    return x*2 + y*2

qua(2, 3)

qua(5, 6)

3.lambda函数

quadratic_sum_ = lambda x, y: x**2 + y**2

quadratic_sum_(4, 5)

quadratic_sum_(3, 4)

五、控制流

1.for循环

list_ = [2, 1, 3, 5, 4, 6]

total = 0
for i in list_:
    if i < 3:
        total = total + i  #total += i

total

total = 0
for i in list_:
    if i == 5:
        break
    total = total + i

total

total=1
for i in list_:
    if i==5:
        continue
    total=total+1

total = 0
for i in list_:
    if i == 5:
        continue        
    total += i

total

total = 0
for i in list_:
    if i == 5:
        pass        
    total += i

total

total = 0
for i in list_:
    total += i

total

a = []
b = []
c = []
for i in list_:
    if i < 3:
        a.append(i)
    elif i > 2 and i < 5:
        b.append(i)
    else:
        c.append(i)

a

b

c

2.while循环

n = 100
total = 0
i = 1
while i <= n:
    total = total + i
    i += 1

n=100
total=0
i=1
while i <=n:
    total=total+1
    i+=1

total

n = 100
total = 0
i = 1
while i <= n:
    total = total + i
    i += 1
    if i == 50:
        break

total

total = 0
for i in list_:
    while i == 5:
        pass        
    total += i

小结：

一、单值——标量类型

1.标量类型：int/float/str/bool/None

2.标量之间的互相转换

3.标量的运算

二、数据结构

1.常见数据结构：tuple/list/dict/set

2.数据结构之间的互相转换

三、列表

1.列表list的索引

2.列表list的运算

3.列表list的属性方法及常用函数

四、函数

1.内置函数:sorted, reversed, zip

2.自定义函数

3.lambda函数

五、控制流

1.for循环：if, elif, else
break, pass, continue

2.while循环

六、Python内置库

import os
import sys
import re
import sqlite3
import tkinter

os.listdir()

os.listdir('input')