What is the `.xts` constructor/how does it work?

Question

I am familiar with as.xts and xts as ways to create an xts object. I have just come across .xts as used in the following:

> x <- .xts(1:3,60*1:3)
> is.xts(x)
[1] TRUE
> x
                    [,1] 
1970-01-01 01:01:00    1
1970-01-01 01:02:00    2
1970-01-01 01:03:00    3

However, I can't find anything about it in the documentation. I note that the same arguments as in the example above would not work for as.xts or xts.

Is .xts some kind of standard R construction?

Answer 1

No, .xts is not any kind of standard. .xts is mainly for internal use, but it's exported for convenience. .xts differs from xts in that xts requires order.by be time-based, whereas .xts expects index (its second argument, akin to order.by) to be numeric.

This is because the index attribute of xts objects is stored internally as a numeric vector with tclass and tzone attributes.