在 R 中应用相同()的行为 [英] Behavior of identical() in apply in R

问题描述

这很奇怪.

apply( matrix(c(1,NA,2,3,NA,NA,2,4),ncol = 2), 1, function(x) identical(x[1], x[2]) )
#[1] FALSE  TRUE  TRUE FALSE
apply( data.frame(a = c(1,NA,2,3),b = c(NA,NA,2,4)), 1, function(x) identical(x[1], x[2]) )
#[1] FALSE FALSE FALSE FALSE
apply( as.matrix(data.frame(a = c(1,NA,2,3),b = c(NA,NA,2,4))), 1, function(x) identical(x[1], x[2]) )
#[1] FALSE FALSE FALSE FALSE

这是由于 joran 如下所示的 names 属性.我可以通过以下方式获得我期望的结果:

This is due to the names attribute as indicated below by joran. I can obtain the result I expected by:

apply( data.frame(a = c(1,NA,2,3),b = c(NA,NA,2,4)), 1, function(x) identical(unname(x[1]), unname(x[2])) ) 

或:

apply( data.frame(a = c(1,NA,2,3),b = c(NA,NA,2,4)), 1, function(x) identical(x[[1]], x[[2]]) ) 

有没有更自然的方法来解决这个问题?似乎应该有一个选项可以忽略属性，就像在 all.equal() 中一样.

Is there a more natural way to approach this? It would seem that there should be an option to ignore attributes, like in all.equal().

推荐答案

可能

mapply(identical, x$a, x$b)
#[1] FALSE  TRUE  TRUE FALSE 

其中 x 是一个数据框.

where x is a data frame.

顺便说一句，对数据框使用 apply 几乎总是一个错误.它会将数据框强制转换为矩阵，这通常会导致意想不到的结果.

As an aside, using apply with a data frame is almost always a mistake. It will coerce the data frame to a matrix which often leads to unexpected results.

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