python之根据python中的变量限制小数

我正在尝试编写一个返回 golden ratio 的程序最多小数位。 我到目前为止是这样的:

def gr(n): 
    a, b = 0, 1 
    for x in range(0, n): 
        a, b = b, a+b 
    else: 
        return(a) 
 
    decimals = int(input("What amount of decimals do you want to see of the golden ratio?")) 
    ratio = gr(41)/gr(40) 
    print(format(ratio, '2f')) 

问题是我找不到一种方法来将ratio 格式化为decimals 中的数字。

请您参考如下方法:

将精度/小数变量传递给 str.format:

decimals = int(input("What amount of decimals do you want to see of the golden ratio?")) 
ratio = gr(41)/gr(40) 
print("{:.{}f}".format(ratio,decimals)) 

例子:

In [3]: decimals = int(input("What amount of decimals do you want to see of the golden ratio?")) 
What amount of decimals do you want to see of the golden ratio?5 
 
In [4]: ratio = gr(41)/gr(40) 
 
In [5]: print("{:.{}f}".format(ratio,decimals)) 
1.61803