Thank you Don so much,
It was very helpful and it worked from the first try. Thanks for the extra
comments on my script.
On Wed, May 11, 2011 at 4:41 PM, MacQueen, Don <macque...@llnl.gov> wrote:
> Try something similar to this:
>
> ## unchanged
> full <- read.table("March_15.dat", sep=",",row.names=NULL,
> as.is=TRUE,skip=1,header=TRUE)
>
>
> ## then convert TIMESTAMP to a date-time class
> full$TIMESTAMP <- as.POSIXct(full$TIMESTAMP)
>
> ## now you can use subset()
> atimeframe <- subset(full,
> TIMESTAMP >= as.POSIXct('2011-03-15 00:00:00') &
> TIMESTAMP <= as.POSIXct('2011-03-15 00:01:30')
> )
>
> Hope this helps.
>
> And a couple of comments on your example.
>
> In an expression like you used,
> timestamp==as.character("2011-03-15 00:01:30")
> just do
> timestamp=="2011-03-15 00:01:30"
>
> "2011-03-15 00:01:30" is already a character string, so you don't have to
> use
>
> as.character() on it.
>
> You used for(), but for() is used to
> make loops, as in
> for (i in 1:10) { }
> which has basically nothing to do with extracting a subset of rows from a
> dataframe.
>
> -Don
>
> --
> Don MacQueen
>
> Lawrence Livermore National Laboratory
> 7000 East Ave., L-627
> Livermore, CA 94550
> 925-423-1062
>
>
>
>
>
> -----Original Message-----
> From: Pablo Rosado <pablojros...@lbl.gov>
> Date: Wed, 11 May 2011 14:21:00 -0700
> To: "r-help@r-project.org" <r-help@r-project.org>
> Subject: [R] selecting data from table with timestamp
>
> >Hi,
> >I am using read.table to get this data that has a timestamp. The data is
> >for many days, but I only want to run the code I wrote only for specific
> >day/days/times. I can´t figure out how to select a timeframe from the
> >list.
> >I have tried using subset() and didn't work
> >
> >I then used:
> >* timestamp[for(timestamp==as.character("2011-03-15 00:00:00" ) |
> >timestamp==as.character("2011-03-15 00:01:30"))]*
> >but it gives me the list of the timestamp for that interval, but I want
> >the
> >complete data.table for that interval, not just the values of the
> >TIMESTAMP
> >column.
> >
> >Here is the script I use to read the table and select the timestamp
> >interval:
> >
> >*full <- read.table("March_15.dat", sep=",",row.names=NULL,
> >as.is=TRUE,skip=1,
> >header=TRUE)
> >minusrows <- full[-1:-2,]
> >names(minusrows)
> >timestamp <- minusrows[,1]
> >timestamp3 <- timestamp[for(timestamp==as.character("2011-03-15 00:00:00"
> >)
> >| timestamp==as.character("2011-03-15 00:01:30"))]
> >timestamp3*
> >
> >An example of what minusrows look like:
> >*
> >> minusrows[1:5,1:4]
> > TIMESTAMP RECORD Batt_Volt_Avg attic.air_temp_cool_north
> >3 2011-03-15 00:00:00 0 13.35 17.99
> >4 2011-03-15 00:00:30 1 13.35 18.00
> >5 2011-03-15 00:01:00 2 13.35 17.98
> >6 2011-03-15 00:01:30 3 13.35 17.99
> >7 2011-03-15 00:02:00 4 13.35 17.97*
> >
> >Thank You so much for your help and time,
> >
> >
> >--
> >*Pablo J. Rosado*, *Ph.D. Student*
> >*Graduate Student Researcher Assistant*
> >*University of California - Berkeley*
> >
> > [[alternative HTML version deleted]]
> >
>
>
--
*Pablo J. Rosado*, *Ph.D. Student*
*Graduate Student Researcher Assistant*
*University of California - Berkeley*
*Lawrence Berkeley National* *Lab** *||* *EET Division* *|| *Heat Island
Group
Office (510) 495-2329
Cell: (787) 399-7635
*
[[alternative HTML version deleted]]
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