Python: how can I round a number downward to next 1000

In python, there's a builtin function round(),
it rounds a number like this:

在python中,有一个内置函数round(),它舍入一个这样的数字:

round(1900, -3) == 2000

is there a builtin function that can round a number downward, like this:

是否有一个内置函数可以向下舍入一个数字,如下所示:

function(1900, -3) == 1000

3 个解决方案

#1

You can use floor division:

您可以使用楼层划分:

def round_down(x, k=3):
    n = 10**k
    return x // n * n

res = round_down(1900)  # 1000

math.floor will also work, but with a drop in performance, see Python integer division operator vs math.floor.

math.floor也可以工作,但性能下降,请参阅Python整数除法运算符与math.floor。

#2

Maybe you can try it this way

也许你可以这样试试

import math
math.floor(1900 / 100) * 100

#3

math.floor([field]) rounds down to next integer

math.floor([field])向下舍入到下一个整数

math.ceil([field]/1000)*1000 rounds down to next 1000

math.ceil([field] / 1000)* 1000向下舍入到下一个1000

Maybe you could make an int cast after that.

也许你可以在那之后做一个int cast。

if you like your syntax with the exponent parameter you could define your own function:

如果您喜欢使用exponent参数的语法,则可以定义自己的函数:

import math

def floorTo10ths(number, exp):
     return int(math.floor(number/10**exp) * 10**exp) 

floorTo10ths(1900, 3)

#1