python_3

list 二维列表

students=[
    ["mike",18,96],
    ["tom",18,56],
    ["tony",19,85]
]

列表的一般输出

print(students[1])#['tom', 18, 56]
print(students[1][1])#18
for student in students:
    for element in student:
        print(element)#挨顺序依次输出所有元素

添加数据

students.append(["rose",17,89])#append在尾部添加数据
print(students)#[['mike', 18, 96], ['tom', 18, 56], ['tony', 19, 85], ['rose', 17, 89]]
students[3].append(["javasript","python"])#向索引3中添加数据
print(students)#[['mike', 18, 96], ['tom', 18, 56], ['tony', 19, 85], ['rose', 17, 89, ['javasript', 'python']]]
print(students[3])#print(students[3])

高维列表

students=[
    ["mike",18,96["javascript","python"]],
    ["tom",18,56],
    ["tony",19,85]
]

矩阵计算

list_1=[
    [1,2,3,4],
    [1,2,3,4],
    [1,2,3,4],
]
list_2=[
    [1,2,3],
    [1,2,3],
    [1,2,3],
    [1,2,3],
]
def matrix_multiply(matrix_1,matrix_2):
    matrix_1_rows=len(matrix_1) #行数
    matrix_1_cols=len(matrix_1[0]) #列数
    matrix_2_cols=len(matrix_2[0])#列数

结果矩阵

result = [[0 for _ in range(matrix_2_cols)]for _ in range(matrix_1_rows)]#_用于占位，因为for和in之间不能为空

乘

 for i in range(matrix_1_rows):
        for j in range(matrix_2_cols):
            for k in range(matrix_1_cols):
                result[i][j]=result[i][j]+matrix_1[i][k]*matrix_2[k][j]
    return result

print(matrix_multiply(list_1,list_2))#[[10, 20, 30], [10, 20, 30], [10, 20, 30]]