Gavin and Stefan,

Both the subset commands and the flag were exactly what I needed. On another
note, I'm dealing with variables that are categorical and have long names
like "Task XYZ", "Task ABC" "Task CCC"

When I try to plot against the probability it doesn't show me the Task name
anymore. How can I map a number back to the actual task name so that I can
understand my plots.

Another problem is I have hundreds of tasks so it is virtually impossible to
show the task names on a plot vs. the probability.

-Melanie



On Mon, Aug 10, 2009 at 1:18 PM, Gavin Simpson <gavin.simpson@ucl.ac.uk>wrote:

> On Mon, 2009-08-10 at 11:17 -0400, mmv.listservs wrote:
> > yy<-poisson2[poisson2$Reboot.Id=="Reboot
> > 2",poisson2$Task.Status=="F",,drop=FALSE]
>
> The above doesn't make any sense and can't be working or doing what you
> think it is doing.
>
> Lets dissect this command:
>
> yy <- poisson2[poisson2$Reboot.Id=="Reboot2",
>                ^^^ so this bit is a flag as to whether we include
>               certain rows
>
>              poisson2$Task.Status=="F", , drop=FALSE]
>               ^^^ Now this bit is saying include columns based on
> whether
>              or not each of your 10000 Task.Status entries == "F" or
>              not
>
> That doesn't make sense. If you want to combine the two clauses, so that
> we return only rows where Reboot.Id=="Reboot2" *and* Task.Status=="F"
> are TRUE, then you need to use the & operator, e.g.
>
> Reboot.Id=="Reboot2" & Task.Status=="F"
>
> This should work:
>
> flag <- with(poisson2, Reboot.Id=="Reboot2" & Task.Status=="F")
> yy <- poisson2[flag, , drop = FALSE]
> ~~                  ^ the blank here means all columns.
>
> As a concrete example as you didn't provide us with the means of
> replicating your problem (while you are reading some introductory
> material on subsetting, also read the Posting Guide to see how to help
> *us* help *you*), we use some dummy data, 3 variables and subset
> conditional upon values of two of them, but return all three columns for
> the result.
>
> ## first set the random seed so we get the same results
> set.seed(123)
> ## now produce some dummy data
> dummy <- data.frame(A = sample(LETTERS[1:4], 100, replace = TRUE),
>                    B = sample(c("T","F"), 100, replace = TRUE),
>                    C = rnorm(100))
> ## view first few rows
> head(dummy)
> ## Lets see which LETTERs we have
> with(dummy, table(A))
> ## Produce table of A vs B
> with(dummy, table(A, B))
> ## As example, select rows of 'dummy' where:
> ## A == "D" *and* B == "F"
> ## which, from table above, should contain 13 rows
> flag <- with(dummy, A == "D" & B == "F")
> want <- dummy[flag,]
> want
> ## notice we get column C as well, because we don't specify which
> ## columns to return...
> ## how many rows? Is this what we expected?
> nrow(want)
>
> Does this help?
>
> The problem with your first posting is that you forgot the trailing
> comma:
>
> all_column_attributes_for_reboot_1 <- poisson2[poisson2
> $Reboot.Id=="Reboot1"]
>                     ^^ needs a , here
>
> 1) choose simpler names - you'll save yourself some RSI not having to
> type them in
> 2) the command should look something like this:
>
> res <- poisson2[poisson2$Reboot.Id=="Reboot1", ]
>
> So now res will contain all rows of poisson2 where Reboot.Id ==
> "Reboot1", with all column attributes. To stop R dropping empty
> dimensions, we might wish to extend this to:
>
> res <- poisson2[poisson2$Reboot.Id=="Reboot1", , drop = FALSE]
> ## Note the empty column indicator -----------^
>
> G
>
> >
> > doesn't work either? Any other ideas?
> >
> > On Mon, Aug 10, 2009 at 11:01 AM, mmv.listservs <mmv.listservs@gmail.com
> >wrote:
> >
> > > How do you access all the column attributes associated with a column
> reboot
> > > instance?
> > >
> > > The variables
> > >
> > > poisson2 ~ a matrix with 10,000 rows and 8 column attributes.
> > >
> > > Things I tried:
> > >
> > >
> > > This command only returns a vector for one of the column attributes
> > > x1_prob <- poisson2$Probability[poisson2$Reboot.Id=="Reboot 1"]
> > >
> > > The command below gave an error:
> > > all_column_attributes_for_reboot_1 <-
> poisson2[poisson2$Reboot.Id=="Reboot
> > > 1"]
> > >
> > > Thank you,
> > >
> > >
> >
> >       [[alternative HTML version deleted]]
> >
> > ______________________________________________
> > R-help@r-project.org mailing list
> > https://stat.ethz.ch/mailman/listinfo/r-help
> > PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> > and provide commented, minimal, self-contained, reproducible code.
> --
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>  Dr. Gavin Simpson             [t] +44 (0)20 7679 0522
>  ECRC, UCL Geography,          [f] +44 (0)20 7679 0565
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