本节主要介绍python数据类型、变量、列表、字典、bool、if语句、for语句、函数等python 基础知识的了解，还未涉及深度学习

编程语言：python 版本：python 3.x

库：NumPy<用于数值计算>、Matplotib<用来画图>

安装：确认python版本

python --version

启动python解释器

C:\Users\Lenovo>python
Python 3.13.1 (tags/v3.13.1:0671451, Dec  3 2024, 19:06:28) [MSC v.1942 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>>

了解数据类型

type（）用于获取数据类型
>>> type(10)
<class 'int'>
>>> type(2.12)
<class 'float'>
>>> type("hello")
<class 'str'>
>>> type('dd')
<class 'str'>
>>> type('d')

了解变量

>>> x=10
>>> print(x)
10
>>> x=100
>>> print(x)
100
>>> y=2.5
>>> x*y
250.0
>>> type(x*y)
<class 'float'>
>>>

了解列表和字典

>>> a=[1,2,3,4,5,100] # 创建列表list
>>> print(a)
[1, 2, 3, 4, 5, 100]
>>> len(a) #列表长度
6
>>> a[0]#访问第一个元素
1
>>> a[5]
100
>>> a[5]=6  #赋值
>>> print(a)
[1, 2, 3, 4, 5, 6]

#切片
>>> a[0:2]
[1, 2]
>>> a[2:]
[3, 4, 5, 6]
>>> a[:3]
[1, 2, 3]
>>> a[:-1]      #第一个元素到最后一个元素的前一个元素
[1, 2, 3, 4, 5] #第一个元素到最后一个元素的前二个元素
>>> a[:-2]
[1, 2, 3, 4]
>>> type(a)
<class 'list'>

了解字典dict

列表根据索引，按照0,1,2, ...的顺序存储值，而字典则以键值对的形 式存储数据。

>>> me={'height':180}   #创建字典
>>> me['weight']=70     #添加元素
>>> me['sex']='man'     #添加元素
>>> me[haircolor]='black' #添加元素
Traceback (most recent call last):  #注意报错
  File "<python-input-42>", line 1, in <module>
    me[haircolor]='black'
       ^^^^^^^^^
NameError: name 'haircolor' is not defined
>>> me['haircolor']='black' 
>>> print(me)
{'height': 180, 'weight': 70, 'sex': 'man', 'haircolor': 'black'}
>>> me
{'height': 180, 'weight': 70, 'sex': 'man', 'haircolor': 'black'}
>>> type(me)
<class 'dict'>

#创建字典第二种方法
>>> I={'weight':50,'height':188,'sex':'woman'}
>>> I
{'weight': 50, 'height': 188, 'sex': 'woman'}
>>>

了解布尔型bool

>>> hungry=True
>>> sleepy=Flase
>>> sleepy=False
>>> type(hungry)
<class 'bool'>
>>> not hungry
False
>>> hungry
True
>>> hungry and sleepy
False
>>> hungry and not sleepy
True
>>> hungry or sleepy
True
>>>

if语句

>>> hungry=True
>>> if hungry:
...     print("I am hungry")
...
I am hungry  #输出的结果
>>> hungry=False
>>> if hungry:
...     print("I am hungry")
... else:
...     print("I am not hungry")
...
I am not hungry  #执行if语句输出的结果
>>>

for语句

>>> for i in [1,2,3]:
...     print(i)
...
1
2
3
>>>

函数

>>> def hello():
...     print("hello world!")
...
>>> hello()
hello world!
>>> def hello(object):
...     print("hello"+object+"!")   #字符串的拼接可以使用+。
...
>>> hello()
Traceback (most recent call last):
  File "<python-input-67>", line 1, in <module>
    hello()
    ~~~~~^^
TypeError: hello() missing 1 required positional argument: 'object'  
>>> hello("cat")
hellocat!
>>> hello(222222)
Traceback (most recent call last):
  File "<python-input-69>", line 1, in <module>
    hello(222222)
    ~~~~~^^^^^^^^
  File "<python-input-66>", line 2, in hello
    print("hello"+object+"!")
          ~~~~~~~^~~~~~~
TypeError: can only concatenate str (not "int") to str
>>>

关闭python解释器时，windos输入ctrl+z,后enter 

                                    linux or mac 输入ctrl+d

>>> ^Z