本篇不具备可读性，慎点。
▍Primitive Datatypes & Operators
＃判断变量b与变量a的值是否相同
b is a
#阶乘
2**4
#字符串的两种写法
"string" 'string'
＃String组合的方式
"Hello" ＋ "World！"
"Hello" "World!"
＃String 索引到Character
"This is a string"[0] #'T'
#String 中可以加入format
"{} can be {}".format("Strings", "interpolated") # "Strings can be interpolated"
#String中format多样的使用方法
"{0} is funny, and {0} is {1}".format("He", "cute") #"He is funny, and he is cute"
"{name} wants to be {adj}".format(name="Wallace", adj="cool") #Wallace wants to be cool
▍Variables and Collections
#print的不同用法
print("I'm Python, Nice to meet you!")
print("I'm Python, Nice to meet you", end="!")
#读取命令行中输入的数据的方法
input_string_var = input("Enter some data: ")
#赋予变量值，无需事先声明变量的类型
some_var = 5
#if的用法
"yahoo!" if 3>2 else 2
#list的操作方式
li = []
li.append(1) #now li is [1]
li.append(2) #now li is [1,2]
li.pop() #now li is [1]
li.append(3) #now li is [1,3]
li[0] #->1
li[-1] #->3 the last one
li = [1,2,3,5]
other_li = [4,5,6]
li[1:3] #It's a closed/open range, so ->[2,3]
li[1:] #->[2,3,5]
li[:3] #->[1,2,3]
li[::2] #->[1,3] select every second entry
li[::-1] #->[5,3,2,1] return a reversed copy of the list
li2 = li[:] #get a copy
del li[2] # li is now [1,2,5]
li.remove(2) # li is now [1,5]
li.insert(1,2) # 第一个变量指position，第二变量是插入的值 li is [1,2,5]
li.index(2) #2在li中的位置，－》1
li.extend(other_li) #now li is [1,2,5,4,5,6]
1 in li #true
len(li) #6
#tup数组
tup = (1,2,3)
tup[0] #->1
type((1)) #
type((1,)) #
type(()) #
len(tup) #->3
tup + (4,5,6) #->(1,2,3,4,5,6)
2 in tup #->True
a,b,c = (1,2,3) #a=1, b=2, c=3
a,*b,c =(1,2,3,4) #a=1, b=[2,3], c=4
a,b = b,a #easy to swap two values
#Dictionaries ##immutable types: ints, floats, strings, tuples
empty_dict = {}
filled_dict = {"one":1, "two":2, "three":3}
valid_dict = {(1,2,3):[1,2,3]}
list(filled_dict.keys()) #->["three", "two", "one"]
list(filled_dict.values()) #->[3,2,1]
filled_dict.get("one") #->1
filled_dict.get("one",4) #->1
filled_dict.get("four", 4) #->4
filled_dict.setdefault("five", 5) #filled_dict["five"] is set to 5
filled_dict.setdefault("five", 6) #由于缺省值已经有了，故依然为5
filled_dict.update({"four":4})
del filled_dict["one"]
#Sets集合
empty_set = set{}
some_set = {1,1,2,3,4,5} #some_set is now {1,2,3,4,5}
filled_set = some_set
filled_set.add(6)
other_set = {3,4,5,6,7}
filled_set & other_set #->{3,4,5,6} #与，获取交集
filled_set | other_set #->{1,2,3,4,5,6,7} ＃或，获取并集
filled_set - other_set #->{1,2}
filled_set ^ other_set #->{1,2,6,7}
{1,2} <= {1,2,3} #True，表示子集
▍Control Flow and Iterables
some_var = 5
#判断流
if some_var >10:
print("a is bigger than 10")
eif some_var < 10:
print("a is smaller than 10")
else:
print("a is indeed 10")
＃循环流
for animal in ["dog", "cat", "mouse"]
print("{} is a mammal".format(animal))
#输出结果
＃dog is a mammal
#cat is a mammal
#mouse is a mammal
for i in range(4)
print(i)
"""
prints:
0
1
2
3
"""
for i in range(4,8)
print(i)
"""
prints:
4
5
6
7
"""
for i in range(4,8,2)
print(i)
"""
prints:
4
6
"""
#循环流 while 循环
x=0
while x<4:
print(x)
#错误抛出
try:
raise IndexError("This is an Index Erro")
except IndexError as e:
pass
except (TypeError, NameError)
pass
else:
print("All Good!")
finally:
print("We can clean up resources here")
＃with 语句，不会有异常抛出
with open("myfile.txt") as f:
for line in f:
print(line)
＃iterable -> Sequence
our_iterator = iter(["one","two","three"])
next(our_iterator) #->"one"
next(our_iterator) #->"two"
next(our_iterator) #->"three"
▍Functions
#函数add
def add(x,y):
return x+y
add(5,6) #11
＃函数var－args
def varargs(*args)
return args
varargs(1,2,3) #(1,2,3)
＃函数keywords
def keyword_args(**args)
return keyword_args
keyword_args(big="foot",loch="ness") #{"big":"foot", "loch":"ness"}
＃函数范围
x＝5
def set_x(num)
x=num
print(x)
set_x(6) #x==5
def set_global_x(num)
global x
x=num
print(x)
set_global_x #x==6
＃函数速写
f=lambda x:x>2
f(3) #True
#上述例子也可以改为
（lambda x:x>2)(3)
＃map函数会根据提供的函数对指定序列作映射
list(map(add_10, [1,2,3])) #［11，12，13］
list(map(max, [1,2,3], [4,5,2])) ＃［4，5，3］
＃filter函数会对指定序列执行过滤操作
list(filter(lambda x:x>5, [3,4,5,6,7]))
#List comprehension
[add10(i) for i in [1,2,3]]
▍Classes
class Human:
species = "H. sapiens"
def __int__(self, name):
self.name = name
self.age=0
▍Models
import math
print(math.sqrt(16))
from math import ceil, floor
print(ceil(3.7)) #不需要使用math.XX
print(floor(3.7)
import math as m
#再度使用之前的例子
print(m.sqrt(16))
from math import * #improt所有的函数
▍Advanced
yield 相当于 return，不同的是它返回的是生成器 ＃可使用next（）
▍Python使用特点
--用缩进 代替大小括号 ＃缩进的空格号要尽量多
