>>>>> "BDR" == Prof Brian Ripley <[EMAIL PROTECTED]>
>>>>> on Tue, 10 Aug 2004 09:11:39 +0100 (BST) writes:
BDR> On Tue, 10 Aug 2004, Martin Maechler wrote:
>> >>>>> "BDR" == Prof Brian Ripley <[EMAIL PROTECTED]>
>> >>>>> on Tue, 10 Aug 2004 05:47:28 +0100 (BST) writes:
>>
BDR> On Tue, 10 Aug 2004, Ross Ihaka wrote:
>> >> Rob Hyndman wrote:
>> >> > When part of a time series is extracted, the time series component is
>> >> > lost. e.g.,
>> >> > x <- ts(1:10)
>> >> > x[1:4]
>> >> >
>> >> > It would be nice if there was a subsetting function [.ts to avoid this
>> >> > problem. However, it is beyond my R-coding ability to produce such a
>> >> > thing. Is someone willing to do it?
>>
BDR> There is a [.ts, in src/library/stats/R/ts.R, and it is documented
BDR> (?"[.ts").
>>
>> >> Have you had a look at "window"? The problem with "["
>> >> its that it can produce non-contiguous sets of values.
>>
BDR> Yes.
>>
>> indeed. window() is what we have been advocation for a long
>> time now ... (but see below).
>>
BDR> If you look in the sources for [.ts you will see,
BDR> commented, the code that was once there to handle cases
BDR> where the index was evenly spaced. But it was removed
BDR> long ago in favour of window(). I tried to consult the
BDR> logs, but it seems that in the shift from CVS to SVN
BDR> recently I can't get at them. I think the rationale
BDR> was that x[ind] should always produce an object of the
BDR> same class.
>>
>> well, that can't have been the only rationale since now
>> x[ind] is *not* of the same class - when the "ts" property is
>> lost in any case.
BDR> `always of the same class' : for all (non-trivial) values of ind.
aah! please excuse my mis-interpretation of meaning "same class
as original x".
Martin
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