Access zoo or xts index
Solution 1
From the help for ?zoo
, there are two convenience methods to access the data in zoo objects:
-
coredata()
returns the data in the zoo object -
index()
returns the index
For example:
x.Date <- as.Date("2003-02-01") + c(1, 3, 7, 9, 14) - 1
x <- zoo(rnorm(5), x.Date)
index(x)
[1] "2003-02-01" "2003-02-03" "2003-02-07" "2003-02-09" "2003-02-14"
coredata(x)
[1] -1.2487943 0.8911630 1.2713133 -0.1024638 0.2989194
Solution 2
In general when you see attr
, this means that this data is an attribute of an object.
attributes
function can be used to dump all attributes as a list, so you can access certain element with $
:
attributes(ObjZoo)$index
attr
gives you direct access to the attribute by its name:
attr(ObjZoo,"index")
In fact this is what index
does:
> zoo:::index.zoo
function (x, ...)
{
attr(x, "index")
}
<environment: namespace:zoo>
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feschet
Updated on June 04, 2022Comments
-
feschet almost 2 years
I am using zoo objects, buy my question also applies to xts objects. It looks to me like it is a one column vector with an index. In my case the index is the vector of dates and the one column vector my data. All is good except that I would like to access the dates (from the index).
For example I have the following result:
ObjZoo <- structure(c(10, 20), .Dim = c(2L, 1L), index = c(14788, 14789), class = "zoo", .Dimnames = list(NULL, "Data")) unclass(ObjZoo) # Data # [1,] 10 # [2,] 20 # attr(,"index") # [1] 14788 14789
I want to get
14789
in a variable or a vector, but I'm not sure how to access it.-
Matt Bannert almost 13 yearsWelcome! Here's a related thread emphasizing the additional relevance of mbq's answer even if Andrie's fits perfectly.
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Dirk Eddelbuettel almost 13 yearsI spend hours looking for that Really? Maybe you should have started with the excellent zoo vignettes.
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Andrie almost 13 years@DirkEddelbuettel, to be fair to the OP, thinking back to my early days with R, I also struggled to make sense of the help files. ts objects were a complete mystery (they still are, to some extent). Yes it's true that I found the answer to this question within 2 minutes of reading ?zoo, but still, I have sympathy with the struggles of the newby.
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