r - as.integer(max(factorize(15))) 的评估

Question

这对我来说似乎很奇怪，我想要一个解释。一世

library(gmp)
factorize(15) # => "3" "5"
max(factorize(15)) # => "5"
as.integer("5") # => 5
as.integer(max(factorize(15))) # => 1 0 0 0 1 0 0 0 1 0 0 0 5 0 0 0

我可以做我想做的事:

max(as.numeric(factorize(15))) # => [1]5

但是让我震惊的是，我不能依赖于在所谓的类似方案的语言中的函数内部嵌套函数。我错过了什么吗？

Answer 1

嗯，答案就在 factorize(15) 的表示中:

> dput(factorize(15))
structure(c(02, 00, 00, 00, 01, 00, 00, 00, 01, 00, 00, 00, 03, 
00, 00, 00, 01, 00, 00, 00, 01, 00, 00, 00, 05, 00, 00, 00), class = "bigz")

和

> dput(max(factorize(15)))
structure(c(01, 00, 00, 00, 01, 00, 00, 00, 01, 00, 00, 00, 05, 
00, 00, 00), class = "bigz")

... max和 as.numeric (实际上， as.double )具有用于 bigz 的方法类，但显然 as.integer才不是:

> methods(max)
[1] max.bigq max.bigz
> methods(as.numeric)
no methods were found
> methods(as.double)
[1] as.double.bigq     as.double.bigz     as.double.difftime as.double.POSIXlt 
> methods(as.integer)
no methods were found

...所以 as.integer对待 bigz对象作为简单的值向量。