R中各栏的平均值，不包括NA [英] Average across Columns in R, excluding NAs

问题描述

我无法想象我是第一个提出这个问题的人，但是我还没有找到解决方案(在这里或其他地方).

I can't imagine I'm the first person with this question, but I haven't found a solution yet (here or elsewhere).

我有一些列，我想在R中求平均值.唯一棘手的方面是某些列包含NA.

I have a few columns, which I want to average in R. The only minimally tricky aspect is that some columns contain NAs.

例如:

Trait Col1 Col2 Col3
DF    23   NA   23
DG    2    2    2
DH    NA   9    9

我想创建一个Col4来对前3列中的条目进行平均，而忽略NA. 因此:

I want to create a Col4 that averages the entries in the first 3 columns, ignoring the NAs. So:

 Trait Col1 Col2 Col3 Col4
 DF    23   NA   23   23
 DG    2    2    2    2
 DH    NA   9    9    9 

理想的情况是这样的:

data$Col4 <- mean(data$Chr1, data$Chr2, data$Chr3, na.rm=TRUE)

但不是.

推荐答案

您要rowMeans()，但重要的是请注意，它具有要设置为TRUE的na.rm自变量.例如:

You want rowMeans() but importantly note it has a na.rm argument that you want to set to TRUE. E.g.:

> mat <- matrix(c(23,2,NA,NA,2,9,23,2,9), ncol = 3)
> mat
     [,1] [,2] [,3]
[1,]   23   NA   23
[2,]    2    2    2
[3,]   NA    9    9
> rowMeans(mat)
[1] NA  2 NA
> rowMeans(mat, na.rm = TRUE)
[1] 23  2  9

匹配您的示例:

> dat <- data.frame(Trait = c("DF","DG","DH"), mat)
> names(dat) <- c("Trait", paste0("Col", 1:3))
> dat
  Trait Col1 Col2 Col3
1    DF   23   NA   23
2    DG    2    2    2
3    DH   NA    9    9
> dat <- transform(dat, Col4 = rowMeans(dat[,-1], na.rm = TRUE))
> dat
  Trait Col1 Col2 Col3 Col4
1    DF   23   NA   23   23
2    DG    2    2    2    2
3    DH   NA    9    9    9

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