[R] Selecting timestamps

[Lauri Nikkinen]

Thanks Bill,

How about situations where time steps are not hourly?

Best regards,
Lauri

2008/2/21, Bill.Venables at csiro.au <Bill.Venables at csiro.au>:
> Since both sequences are in hourly steps, there is a fairly easy way to
> do this:
>
> > before <- colSums(outer(seq1, seq2, "<"))
> > sort(c(seq1[before], seq1[before+1]))
>
> This uses the fact that both sequences are in hourly time steps, so the
> time stamp 'just after' the member of seq2 is the next one to the one
> 'just before'.  Relaxing this assumption, if needed, is left as an easy
> exercise.
>
> Bill Venables
>
> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]
> On Behalf Of Lauri Nikkinen
> Sent: Thursday, 21 February 2008 5:04 PM
> To: r-help at stat.math.ethz.ch
> Subject: [R] Selecting timestamps
>
> R-users,
>
> I have two vectors (of timestamps)
>
> d1 <- as.POSIXct(strptime("2.2.2002 07:00", format="%d.%m.%Y %H:%M"))
> d2 <- as.POSIXct(strptime("4.2.2002 07:00", format="%d.%m.%Y %H:%M"))
> seq1 <- seq(d1, d2, "hours")
> seq1
>
> d3 <- as.POSIXct(strptime("2.2.2002 15:22", format="%d.%m.%Y %H:%M"))
> d4 <- as.POSIXct(strptime("3.2.2002 18:12", format="%d.%m.%Y %H:%M"))
> seq2 <- seq(d3, d4, "hours")
> seq2
>
> How to select timestamps from seq1 which are just before and after of
> particular timestamp in seq2?
> The resulting vector should look like this in this example:
>
> "2002-02-02 15:00:00 Normaaliaika"
> "2002-02-02 16:00:00 Normaaliaika"
> "2002-02-02 16:00:00 Normaaliaika"
> "2002-02-02 17:00:00 Normaaliaika"
> "2002-02-02 17:00:00 Normaaliaika"
> "2002-02-02 18:00:00 Normaaliaika"
> "2002-02-02 18:00:00 Normaaliaika"
> etc.
>
> Thank you,
> Lauri
>
>
> > sessionInfo()
> R version 2.6.0 (2007-10-03)
> i386-pc-mingw32
>
> locale:
> LC_COLLATE=Finnish_Finland.1252;LC_CTYPE=Finnish_Finland.1252;LC_MONETAR
> Y=Finnish_Finland.1252;LC_NUMERIC=C;LC_TIME=Finnish_Finland.1252
>
> attached base packages:
> [1] stats     graphics  grDevices utils     datasets  methods   base
>
> other attached packages:
> [1] RODBC_1.2-3
>
> loaded via a namespace (and not attached):
> [1] tools_2.6.0
>
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>
>