将任意数字向上/向下舍入到任意间隔
您可以使用 模运算符 %% 轻松地将数字四舍五入到特定区间。
功能：
round.choose <- function(x, roundTo, dir = 1) {
if(dir == 1) { ##ROUND UP
x + (roundTo - x %% roundTo)
} else {
if(dir == 0) { ##ROUND DOWN
x - (x %% roundTo)
}
}
}
示例：
> round.choose(17,5,1) #round 17 UP to the next 5th
[1] 20
> round.choose(17,5,0) #round 17 DOWN to the next 5th
[1] 15
> round.choose(17,2,1) #round 17 UP to the next even number
[1] 18
> round.choose(17,2,0) #round 17 DOWN to the next even number
[1] 16
工作原理：
模运算符%% 确定第一个数字除以第二个数字的余数。在您感兴趣的数字上添加或减去此间隔基本上可以将该数字“四舍五入”到您选择的间隔。
> 7 + (5 - 7 %% 5) #round UP to the nearest 5
[1] 10
> 7 + (10 - 7 %% 10) #round UP to the nearest 10
[1] 10
> 7 + (2 - 7 %% 2) #round UP to the nearest even number
[1] 8
> 7 + (100 - 7 %% 100) #round UP to the nearest 100
[1] 100
> 7 + (4 - 7 %% 4) #round UP to the nearest interval of 4
[1] 8
> 7 + (4.5 - 7 %% 4.5) #round UP to the nearest interval of 4.5
[1] 9
> 7 - (7 %% 5) #round DOWN to the nearest 5
[1] 5
> 7 - (7 %% 10) #round DOWN to the nearest 10
[1] 0
> 7 - (7 %% 2) #round DOWN to the nearest even number
[1] 6
更新：
方便的 2 参数版本：
rounder <- function(x,y) {
if(y >= 0) { x + (y - x %% y)}
else { x - (x %% abs(y))}
}
正值y 值roundUp，负值y 值roundDown：
# rounder(7, -4.5) = 4.5, while rounder(7, 4.5) = 9.
或者....
根据标准舍入规则自动向上舍入或向下的功能：
Round <- function(x,y) {
if((y - x %% y) <= x %% y) { x + (y - x %% y)}
else { x - (x %% y)}
}
如果x 值是> 在舍入值y 的后续实例之间的中间值，则自动舍入：
# Round(1.3,1) = 1 while Round(1.6,1) = 2
# Round(1.024,0.05) = 1 while Round(1.03,0.05) = 1.05