R:将嵌套的for循环转换为应用函数

data = [
    [1, 2, 3],
    [4, 5, 6],
    [7, 8, 9]
]

sum_of_squares = 0
for row in data:
    for element in row:
        sum_of_squares += element ** 2

print(sum_of_squares)

def square(x):
    return x ** 2

def sum_of_squares(data):
    total = 0
    for row in data:
        for element in row:
            total += square(element)
    return total

data = [
    [1, 2, 3],
    [4, 5, 6],
    [7, 8, 9]
]

print(sum_of_squares(data))

def square(x):
    return x ** 2

data = [
    [1, 2, 3],
    [4, 5, 6],
    [7, 8, 9]
]

sum_of_squares = sum(map(square, (element for row in data for element in row)))
print(sum_of_squares)