python怎么计算面积？

#!/usr/bin/python

#-*-coding:utf-8 -*-

name = raw_input("Please input your name here : ")

if name == '':

    print("we don't like anonymous")

else:

    choose = input("Which shape would you like to choose 1:Rectangle, 2:Square, 3:Triangle or 4 Round? :")

    if choose == 1:

        width, height = map(int, raw_input("Input width and height here, like 5 8 :").split())

        print( "Area = %d" % (width * height))

    elif choose == 2:

        length = input("Input width and height here, like 4:")

        print( "Area = %d" % length ** 2)

    elif choose == 3:

        width, height = map(int, raw_input("Input width and height here, like 5 8 :").split())

        print( "Area = %d" % (width * height / 2))

    elif choose == 4:

        diameter = input("Input diameter here like 3 :")

        print ("Area = %.2f" % (3.14 * (diameter / 2) ** 2))

    else:

        print( "Invalid choose")