[R] subset dataframe/list

[David Winsemius]

On Jun 1, 2009, at 1:01 PM, Cecilia Carmo wrote:

> Hi R-helpers!
>
> I have the following object:
>> head(coeficientes)
>    caedois           b1           b2           b3
> 1       1    0,033120395 -20,29478338 -0,274638864
> 2       2   -0,040629634  74,54239889 -0,069958424
> 3       5   -0,001116816   35,2398622  0,214327185
> 4      10     0,171875
> 5      14   0,007288399  40,06560548 -0,081828338
> 6      15   0,027530346  0,969969409  0,102775555
>
> I´ve tried to subset it like this:
>> coefSelected<-subset(coeficientes,"b1">0)
> but it does nothing
>
> Then I’ve tried:
>> coefSelected<-subset(coeficientes,b1>0)
> But I´ve got the following
> Warning message:
> In Ops.factor(b1, 0) : > not meaningful for factors

So the b1 variable is a factor. How it got that way is hard to  
determine.
>
>
> So I’ve tried:
>> coefSelected<-subset(coeficientes,coeficientes$b1>0)
> Warning message:
> In Ops.factor(coeficientes$b1, 0) : > not meaningful for factors
>
> I´ve done
>> mode(coeficientes)
> [1] "list"

So coeficientes could be just a list or  more likely it is a data.frame.

What happens if you convert b1 to numeric? Try this way:

coeficientes$b1 <- as.numeric( as.character(coeficientes$b1) )

Then try subsetting.

See: http://cran.r-project.org/doc/FAQ/R-FAQ.html#How-do-I-convert-factors-to-numeric_003f

>
>
> But I don´t know how to handle it!
> Coul anyone help me?
> Thanks,
>
> Cecília Carmo (Universidade de Aveiro – Portugal
>
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David Winsemius, MD
Heritage Laboratories
West Hartford, CT