将 NA 替换为 data.table 同一列的平均值 [英] Replace NAs with mean of the same column of a data.table

问题描述

我想用同一列的平均值替换 DATA TABLE 列中存在的 NA.我正在做以下事情.但它不起作用.

I want to replace NAs present in a column of a DATA TABLE with the mean of the same column. I am doing the following. But it is not working.

ww <- data.table(iris)

ww <- ww[1:5 , ]

ww[1,1] <- NA

   Sepal.Length Sepal.Width Petal.Length Petal.Width Species
1:           NA         3.5          1.4         0.2  setosa
2:          4.9         3.0          1.4         0.2  setosa
3:          4.7         3.2          1.3         0.2  setosa
4:          4.6         3.1          1.5         0.2  setosa
5:          5.0         3.6          1.4         0.2  setosa


ww[is.na(Sepal.Length) , Sepal.Length:= mean(Sepal.Length, na.rm = T)]

   Sepal.Length Sepal.Width Petal.Length Petal.Width Species
1:          NaN         3.5          1.4         0.2  setosa
2:          4.9         3.0          1.4         0.2  setosa
3:          4.7         3.2          1.3         0.2  setosa
4:          4.6         3.1          1.5         0.2  setosa
5:          5.0         3.6          1.4         0.2  setosa

为什么我用 NaN 代替 NA 而它应该是其余值(4.9、4.7、4.6、5.0)的平均值?

Why am I getting NaN in place of NA when it should have been the mean of the rest of the values (4.9, 4.7, 4.6, 5.0)?

如果这种语法有问题，有什么替代方法可以实现?

What is the alternate of acheiving this in case something is wrong with this syntax?

我想要数据表的语法.

推荐答案

na.aggregate zoo 包中的 NAs 替换为同列非 NAs 的均值:

na.aggregate in the zoo package replaces NAs with the mean of the non-NAs in the same column:

library(zoo)

ww[, Sepal.Length := na.aggregate(Sepal.Length)]

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