python - python - 如何连接四舍五入数字的字符串？

Question

我无法找出在 python 中连接字符串的错误。

目标是将数字格式化为字符串，我可以以一致的长度打印该字符串。

我编写了以下代码:

def numPrint(number,roundplace):
    num = round(number, roundplace)
    if num > 0:
        output = ('+' + str(num))
    elif num < 0:
        output = (str(num))
    else:
        output = (' 0.' + '0' * roundplace)    

    if len(output) < (3 + roundplace):
        output2 = (output + '0')
    else:
        output2 = output

    return output2

print(numPrint(0.001, 3))
print(numPrint(0, 3))
print(numPrint(-0.0019, 3))
print(numPrint(-0.01, 3))
print(numPrint(0.1, 3))

我希望它打印:

+0.001
 0.000
-0.002
-0.010
+0.100

但是，我越来越

+0.001
 0.000
-0.002
-0.010
+0.10

如何将“0”添加到最后一个以使其正常工作？

Answer 1

您只是忘记将 output2 乘以零:

if len(output) < (3 + roundplace):
    output2 = (output + ('0'*(3 + roundplace - len(output))))
else:
    output2 = output

或者，如果您不介意使用内置函数:

output2 = output.ljust(3 + roundplace, '0')