[R] Subseting a data.frame

[William Dunlap]

> What I need is to select only those records for which there are more than two default
> frequencies (defa_frequency),

Here is one way.  There are many others:
   > dat <- data.frame( # slightly less trivial example
        basel_asset_class=c(4,8,8,8,74,3,74),
        defa_frequency=(1:7)/8)
   > count_by_class <- with(dat, ave(numeric(length(basel_asset_class)), basel_asset_class, FUN=length))
   > cbind(dat, count_by_class) # see what we just computed
     basel_asset_class defa_frequency count_by_class
   1                 4          0.125              1
   2                 8          0.250              3
   3                 8          0.375              3
   4                 8          0.500              3
   5                74          0.625              2
   6                 3          0.750              1
   7                74          0.875              2
   > mydat[count_by_class>1, ] # I think this is what you are asking for
     basel_asset_class defa_frequency
   2                 8          0.250
   3                 8          0.375
   4                 8          0.500
   5                74          0.625
   7                74          0.875

Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com


> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf
> Of Katherine Gobin
> Sent: Thursday, October 17, 2013 11:05 AM
> To: Bert Gunter
> Cc: r-help at r-project.org
> Subject: Re: [R] Subseting a data.frame
> 
> Correction. (2nd para first three lines)
> 
> Pl read following line
> 
> What I need is to select only those records for which there are more than two default
> frequencies (defa_frequency), Thus, there is only one default frequency = 0.150 w.r.t
> basel_asset_class = 4 whereas there are default frequencies w.r.t. basel aseet class 4,
> 
> 
> as
> 
> What I need is to select only those records for which there are more than two default
> frequencies (defa_frequency), Thus, there is only one default frequency = 0.150 w.r.t
> basel_asset_class = 4 whereas there are THREE default frequencies w.r.t. basel aseet
> class 8,
> 
> 
> 
> I alpologize for the incovenience.
> 
> Regards
> 
> KAtherine
> 
> 
> 
> 
> 
> 
> 
> 
> On , Katherine Gobin <katherine_gobin at yahoo.com> wrote:
> 
>  I am sorry perhaps  was not able to put the question properly. I am not looking for the
> subset of the data.frame where the basel_asset_class is > 2. I do agree that would have
> been a basic requirement. Let me try to put the question again.
> 
> I have a data frame as
> 
> mydat = data.frame(basel_asset_class = c(4, 8, 8 ,8), defa_frequency = c(0.15, 0.07, 0.03,
> 0.001))
> 
> # Please note I have changed the basel_asset_class to 4 from 2, to avoid confusion.
> 
> > mydat
>   basel_asset_class defa_frequency
> 1                 4          0.150
> 2                 8          0.070
> 3                 8          0.030
> 4                 8          0.001
> 
> 
> 
> This is just an representative example. In reality, I may have no of basel asset classes. 4, 8
> etc are the IDs can be anything thus I cant hard code it as subset(mydat,
> mydat$basel_asset_class > 2).
> 
> 
> What I need is to select only those records for which there are more than two default
> frequencies (defa_frequency), Thus, there is only one default frequency = 0.150 w.r.t
> basel_asset_class = 4 whereas there are default frequencies w.r.t. basel aseet class 4,
> similarly there could be another basel asset class having say 5 default frequncies. Thus, I
> need to take subset of the data.frame s.t. the no of corresponding defa_frequencies is
> greater than 2.
> 
> The idea is we try to fit exponential curve Y = A exp( BX ) for each of the basel asset
> classes and to estimate values of A and B, mathematically one needs to have at least two
> values of X.
> 
> I hope I may be able to express my requirement. Its not that I need the subset of mydat
> s.t. basel asset class is > 2 (now 4 in revised example), but sbuset s.t. no of default
> frequencies is greater than or equal to 2. This 2 is not same as basel asset class 2.
> 
> Kindly guide
> 
> With warm regards
> 
> Katherine Gobin
> 
> 
> 
> 
> On Thursday, 17 October 2013 9:33 PM, Bert Gunter <gunter.berton at gene.com> wrote:
> 
> "Kindly guide" ...
> 
> This is a very basic question, so the kindest guide I can give is to read an Introduction to R
> (ships with R) or a R web tutorial of your choice so that you can learn how R works
> instead of posting to this list.
> 
> Cheers,
> Bert
> 
> 
> 
> 
> On Wed, Oct 16, 2013 at 11:55 PM, Katherine Gobin <katherine_gobin at yahoo.com>
> wrote:
> 
> Dear Forum,
> >
> >I have a data frame as
> >
> >mydat = data.frame(basel_asset_class = c(2, 8, 8 ,8), defa_frequency = c(0.15, 0.07,
> 0.03, 0.001))
> >
> >> mydat
> >  basel_asset_class defa_frequency
> >1                 2          0.150
> >2                 8          0.070
> >3                 8          0.030
> >4                 8          0.001
> >
> >
> >I need to get the subset of this data.frame where no of records for the given
> basel_asset_class is > 2, i.e. I need to obtain subset of above data.frame as (since there
> is only 1 record, against basel_asset_class = 2, I want to filter it)
> >
> >> mydat_a
> >  basel_asset_class defa_frequency
> >1                 8          0.070
> >2                 8          0.030
> >3                 8          0.001
> >
> >Kindly guide
> >
> >Katherine
> >        [[alternative HTML version deleted]]
> >
> >
> >______________________________________________
> >R-help at 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.
> >
> >
> 
> 
> --
> 
> Bert Gunter
> Genentech Nonclinical Biostatistics
> 
> (650) 467-7374
> 	[[alternative HTML version deleted]]