你如何 round() python 中的 map 函数？

Question

I am trying to do this,

  print(list(round(map(radius, cirumfrence), 1)))

but it comes up with this error:/

    print(list(round(map(radius, cirumfrence), 1)))
TypeError: type map doesn't define __round__ method

Anyone know what the problem is? Thanks!

Here is the whole code.

  cirumfrence = [2.7, 69, 7, 2]

  radius = lambda circ: ((circ)/2*math.pi)

  print(list(map(round(radius, cirumfrence))))

Answer 1

I would use a list comprehension:

cirumfrence = [2.7, 69, 7, 2]

radius = lambda circ: ((circ)/2*math.pi)

new_lst = [round(radius(x),2) for x in cirumfrence]

Output: [4.24, 108.38, 11.0, 3.14]