如何测试对象是否为向量 [英] How to test if object is a vector

问题描述

如何测试一个对象是否为向量，即模式logical、numeric、complex 或character?is.vector 的问题在于它还会为列表和其他类型返回 TRUE:

How to test if an object is a vector, i.e. mode logical, numeric, complex or character? The problem with is.vector is that it also returns TRUE for lists and perhaps other types:

> is.vector(list())
[1] TRUE

我想知道它是否是原始类型的向量.是否有本机方法，还是必须使用存储模式?

I want to know if it is a vector of primitive types. Is there a native method for this, or do I have to go by storage mode?

推荐答案

只有原始函数，所以我假设您想知道向量是否是原子类型之一.如果你想知道一个对象是否是原子的，使用 is.atomic.

There are only primitive functions, so I assume you want to know if the vector is one of the atomic types. If you want to know if an object is atomic, use is.atomic.

is.atomic(logical())
is.atomic(integer())
is.atomic(numeric())
is.atomic(complex())
is.atomic(character())
is.atomic(raw())
is.atomic(NULL)
is.atomic(list())        # is.vector==TRUE
is.atomic(expression())  # is.vector==TRUE
is.atomic(pairlist())    # potential "gotcha": pairlist() returns NULL
is.atomic(pairlist(1))   # is.vector==FALSE

如果您只对您提到的原子类型的子集感兴趣，最好明确测试它们:

If you're only interested in the subset of the atomic types that you mention, it would be better to test for them explicitly:

mode(foo) %in% c("logical","numeric","complex","character")

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