格式时遇到问题我小数

Question

我需要我的输出，在3位小数

def main(): 

    n = eval(input("Enter the number of random steps: ")) 
    t = eval(input("Enter the number of trials: ")) 

    pos = 0 
    totalPosition = 0 
    totalSum = 0 
    L = list() 

    import random 
    A = [-1, 1] 

    for x in range(t): 
     pos = 0 
     for y in range(n): 
      step = random.choice(A) 
      pos += step 


     totalPosition += abs(pos) 
     totalSum += pos**2 

    pos1 = totalPosition/t 
    totalSum /= t 
    totalSum = totalSum**0.5 


    print("The average distance from the starting point is a %.3f", % pos1) 
    print("The RMS distance from the starting point is %.3f", % totalSum) 

main() 

我不断收到语法错误，我是否尝试同时使用“％”字符和{0：.3f} .format （pos1）方法。有人知道我要去哪里错了吗？

谢谢！

Answer 1

对于字符串插值，你需要把%运营权背后的格式字符串：

print ("The average distance from the starting point is a %.3f" % pos1) 

这是一个比较明显的，如果你用更现代的format方式：

print ("The average distance from the starting point is a {:.3f}".format(pos1)) 

Answer 2

您在字符串文字和％符号之间有逗号。删除这些。

print("The average distance from the starting point is a %.3f" % pos1) 

Answer 3

你得到print和格式困惑：

print("The average distance from the starting point is a %.3f" % pos1) 

你真的应该，虽然更喜欢新的样式格式：

print("Whatever {:.3f}".format(pos1)) 

或者，如果你真的想：

print("Whatever", format(pos1, '.3f')) 

Answer 4

你不需要在打印功能,只是%足够例如：

print("The RMS distance from the starting point is %.3f", % totalSum) 
                 ^remove this , 

，如：

print("The RMS distance from the starting point is %.3f" % totalSum)