列表推導式

概念：提供了一種創建列表的簡單快速的途徑

(1) 一般形式

myList = [x for x in range(10)]

?

#分解後

myList = []

for x in range(10):

    myList.append(x)

print(myList)

(2) 一般形式+判斷

myList = [x for x in range(1,21) if x>10]

myList = [x for x in range(1,21) if x%2==0 and x<10]

(3) 生成列表嵌套

#第三種 生成列表嵌套
 

myList = [[x,x+1,x+2] for x in range(10)]

print(myList)

(4) 循環嵌套

#第四種 循環嵌套

myList = [x for x in range(3) for y in range(10)]

myList = [[x,y] for x in range(3) for y in range(10)]

3*4矩陣列表

myList = [

    [1,2,3,4],

    [5,6,7,8],

    [9,10,11,12]

]

變成4*3矩陣列表

newList = [[v[i] for v in myList] for i in range(4)]
 

拆分

newList = []

for i in range(4):

    appendList = []

    for v in myList:

        # print(v[i])

        appendList.append(v[i])

    newList.append(appendList)

print(newList)

(5) 字典推導式

Dict = {k:v for k,v in [(‘a‘,‘a‘),(‘b‘,‘b‘)]}

print(Dict)

python 基礎(六)