xtabs 用 NA 和 na.action = na.pass 在 R 中计数 [英] xtabs counts with NA and na.action = na.pass in R

问题描述

我有以下 data.frame:

x <- data.frame(A = c("Y", "Y", "Z", NA),
                B = c(NA, TRUE, FALSE, TRUE),
                C = c(TRUE, TRUE, NA, FALSE))

我需要计算下表:

A     B  C
Y     1  2
Z     0  0
<NA>  1  0

但是，即使使用 na.action = na.pass，我也无法使用 xtabs 实现此结果:

However I am unable to achieve this result with xtabs, even with na.action = na.pass:

xtabs(formula = cbind(B, C) ~ A,
      data = x,
      addNA = TRUE,
      na.action = na.pass)

A       B  C
  Y        2
  Z     0   
  <NA>  1  0

来自?xtabs:

na.action
一个函数，它指示当数据包含 NA.如果未指定，并且 addNA 为真，则设置为na.pass.当它是 na.pass 并且公式有左侧时(与counts)，使用 sum(*, na.rm = TRUE) 代替 sum(*) 来表示计数.

na.action
a function which indicates what should happen when the data contain NAs. If unspecified, and addNA is true, this is set to na.pass. When it is na.pass and formula has a left hand side (with counts), sum(*, na.rm = TRUE) is used instead of sum(*) for the counts.

添加NA
逻辑指示 NA 是否应该获得单独的级别并被计数，使用 addNA(*, ifany=TRUE) 并设置默认值无行动.

addNA
logical indicating if NAs should get a separate level and be counted, using addNA(*, ifany=TRUE) and setting the default for na.action.

作为一种解决方法，我可以将 NA 替换为 FALSE:

As a workaround, I can replace the NA by FALSE:

x[is.na(x$B), "B"] <- FALSE
x[is.na(x$C), "C"] <- FALSE

xtabs(formula = cbind(B, C) ~ A,
      data = x,
      addNA = TRUE)

A      B C
  Y    1 2
  Z    0 0
  <NA> 1 0

或者我可以使用聚合:

aggregate(formula = cbind(B, C) ~ addNA(A),
          data = x,
          FUN = sum,
          na.rm = TRUE,
          na.action = na.pass)

  addNA(A) B C
1            Y 1 2
2            Z 0 0
3         <NA> 1 0

但是如何用 xtabs 得到这个表而不用 FALSE 替换 NA ?

But how get this table with xtabs without replacing NA by FALSE?

推荐答案

将 na.action=na.pass 更改为 na.action=NULL.

xtabs(formula = cbind(B, C) ~ A,
      data = x,
      addNA = TRUE,
      na.action = NULL)

A      B C
  Y    1 2
  Z    0 0
  <NA> 1 0

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