Question

我在第一列有3个data.table工作日，在列的其余部分有数字。在第一个DT(DT1)中，每列上有7行和n列（n>2）数字数据。剩下的DT (DT2, DT3)有7行2列，有一个数字列。

我想替换每个列中的元素（工作日列除外），其中DT2中的元素小于或等于DT3中的元素，且工作日相同。

x = c(8.38877450980392, 7.94021071115013, 7.95032679738562, 7.44576124567474, 
8.83645276292335)
y = c(83.8877450980392, 79.4021071115013, 79.5032679738562, 74.4576124567474, 
88.3645276292335)
DT1 = data.table(WeekDay = c("Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"), a = abs(rnorm(7)*100), b = abs(rnorm(7)*100), c = abs(rnorm(7)*100), d = abs(rnorm(7)*100))
DT2 = data.table(WeekDay = c("Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"), criteria = x)
DT3 = data.table(WeekDay = c("Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"), Replace_Value = y)

有没有办法在没有循环的情况下完成它？请仅使用基础R？谢谢。

Answer 1

这应该这样做：

setkey(DT1, WeekDay)
setkey(DT2, WeekDay)
mx.data <- as.matrix(DT1[, letters[1:4], with=F])
(DT1[DT2][DT3][, letters[1:4]:=as.data.table(ifelse(mx.data < criteria, Replace_Value, mx.data))])

首先，我将所有表合并为Shadow建议。然后，使用我使用DT1中的数据创建的矩阵，我对ifelse使用criteria，这应该为每列回收criteria。然后，我首先使用ifelse替换运算符将data.table转换为a-d到:=列，然后分配DT1的结果。

正如影子所说，我必须更改您的标准，以便他们拥有正确的天数。此外，我必须使您的标准变得更大，因为它们从未被满足（crtieria中的值始终大于x = c(8.38877450980392, 7.94021071115013, 7.95032679738562, 7.44576124567474, 8.83645276292335, 50, 25) y = c(83.8877450980392, 79.4021071115013, 79.5032679738562, 74.4576124567474, 88.3645276292335, 50, 25) set.seed(1) DT1 = data.table(WeekDay = c("Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"), a = abs(rnorm(7)*100), b = abs(rnorm(7)*100), c = abs(rnorm(7)*100), d = abs(rnorm(7)*100)) DT2 = data.table(WeekDay = c("Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"), criteria = x * 7) DT3 = data.table(WeekDay = c("Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"), Replace_Value = y)）。以下是我对您的数据所做的工作：

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如何通过条件（没有循环）替换data.table中的元素？

1 个答案: