r - why the object is vector?

Question

> x=c(1,2,3,4,5)  
> x1=list(n1=1,n2=2,n3=x)  
> is.vector(x1)  

[1] TRUE

> is.list(x1)  

[1] TRUE

why is.vector(x1)=true?i can't understand.

Answer 1

From ?is.vector

If mode = "any", is.vector may return TRUE for the atomic modes, list and expression.

You can specify the mode if you do not want is.vector to return TRUE for a list

> is.vector(x1, mode='numeric')
[1] FALSE

> is.vector(x, mode='numeric')
[1] TRUE