Python學習筆記

name=input("What is your name?")
print("my_name","Eric") #會以空白隔開 => my_name eric
print("a","b",sep="<->") #會以<->當作分隔 => a<->b
print("a","b",end=' ') #以空格當結尾,預設是換行 => a b
n, m = map(int, input().split(',', 2)) #輸入兩個用逗號隔開的整數

dic={'a':1,'b':2,'c':4}
print(dic['c'])  #=>4

#print all keys
for i in dic:
    print(i,end=' ')
    
#print all values
for i in dic.values():
    print(i,end=' ')

s=set() #建立空集合
s={i for i in range(5)} #s={0,1,2,3,4}
s.add(5) #加入元素
s.remove(4) #刪除元素
print(s) #{0, 1, 2, 3, 5}
if 2 in s: #判斷2是否在set理 =>True

A=['a string',23,100.232,'o']
print(A[2])  #=>100.232

B=[[None for _ in range(10)] for _ in range(10)] #10x10 list

t=(1,2,3) #or t=1,2,3
print(t[1])  #=>2

a=5
if a<4:
    print("a<4")
elif a>=4 and a<6:
    print("a>=4 且 a<6")  
else:
    print("a>=6")
#=> a>=4 且 a<6

r=range(5,10)  #5,6,7,8,9
print(r[4]) #=>9
r2 = range(5, 50, 5)  #5,10,15,20
print(r2[3]) #=>20

for i in range(2,10,3):  #起始值，結束值，增加值
    print(i,end=' ') #2 5 8
a=[3,1,2,3]
for i in a:
    print(i,end=' ') #=>3 1 2 3
i=0
while(i<10):
    print(i,end=' ') 
    i+=1
#=>0 1 2 3 4 5 6 7 8 9

s="hello world"
arr=s.split('o') 
print(arr)  #=>['hell', ' w', 'rld']
s2='---'.join(arr)
print(s2)  #=>hell--- w---rld

a=[6,3,2,1,3,2,5]
print(len(a)) #7
print(max(a)) #6
print(a.count(3)) #3出現2次輸出2
a.insert(2,100) #在index=2的位置插入100
a.remove(2) #移除第一個2
a.reverse() #反轉
print(a) #[5, 2, 3, 1, 100, 3, 6]

b=[1,2,3,4,5]
del b[1:3] #刪除index1到index3前一個的所有元素 => b=[1, 4, 5]
a.append(b) #將b塞到a的最後面 => a=[5, 2, 3, 1, 100, 3, 6, [1, 4, 5]]
print(a[-1][2]) #-1代表最後一個元素, =>5
a.clear() #清空

c=[]
for i in range(10):
    c.append(i)
print(c) #[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

d=[i for i in range(10)]
print(d) #[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

#只取小於5的奇數
e=[i for i in d if i<=5 and i&1]
print(e) #[1, 3, 5]

class Student:
    def __init__(self,id,seat):
        self.id=id
        self.seat=seat
    
    def __str__(self):
       return f'My ID is {self.id}, and my seat number is {self.seat}.'

    def change_seat(self,newSeat):
        self.seat=newSeat
        
student=Student("848392","3A2B")
student.change_seat("8A7B")
print(student)  #My ID is 848392, and my seat number is 8A7B.

import numpy as np

a=np.array([1,2,3]) # 一維
b=np.array([[1,2,3],[4,5,6]]) #二維
c=np.zeros(5) #[0,0,0,0,0]
d=np.zeros((2,3)) #2×3的陣列，初始化為0
e=np.ones((3,4,5)) #3×4×5的陣列，初始化為1

a=np.array([1,2,3])
b=np.array([2,3,4])
print(a+b)  #[3 5 7]

c=[1,2,3]
d=[2,3,4]
print(c+d) #[1, 2, 3, 2, 3, 4]

a=np.array([[1,2],
            [2,3]])
b=np.array([[3,4],
            [4,5]])

print(a.dot(b))  #[[11 14]
                 # [18 23]]

a = np.array([3, 5, 6])
b = np.array([2, 6, 1])
print(a @ b) #: 6+30+6=42

a=[1,2,3,4,5]
b=a[-1]  #最後一個元素
c=a[::-1]  #反向讀取 [5,4,3,2,1]
d=a[3::-1]  #從index=3開始反向讀取 [4,3,2,1]

pip install [name]

pip list

pip install -e [file name]