[R] subscripting issues

[Petr Pikal]

Hi

On 25 Jan 2007 at 10:44, Marc Schwartz wrote:

From:           	Marc Schwartz <marc_schwartz at comcast.net>
To:             	ablukacz <ablukacz at utm.utoronto.ca>
Date sent:      	Thu, 25 Jan 2007 10:44:18 -0600
Copies to:      	r-help at stat.math.ethz.ch
Subject:        	Re: [R] subscripting issues
Send reply to:  	marc_schwartz at comcast.net
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> On Thu, 2007-01-25 at 11:04 -0500, ablukacz wrote:
> > Dear All,
> > 
> > I have a very simple problem.
> > I have a matrix called Predictors with headers X0...X24
> > >dim(Predictors)
> > [1] 79 25
> > 
> >   Predictors
> >            X0        X1        X2        X3        X4        X5     
> >              X6
> > 1  13.741200 12.148036 11.909435 11.671669 11.238207 10.864697
> > 10.566351 2  10.240200 11.883900 11.529400 11.515050 11.411640
> > 11.105800 10.813457
> > 
> > 
> > 
> > I would like to take each row and all the corresponding columns with
> > out the header. I tried  Predictors[1,1:25] but that retains the
> > headers.
> > 
> > 
> > Any suggestions.
> > 
> > Thanks,
> > 
> > Agnes
> 
> The column names of X0, etc. suggest that Predictors is a data frame
> created by the use of one of the read.table() family of functions, not

although you are probably right, it could be matrix as well

> is.data.frame(zeta)
[1] TRUE
> is.matrix(zeta)
[1] FALSE
>
> zetam<-as.matrix(zeta)
> zetam
  tepl tio2 al2o3  iep
1   60    1   3.5 5.65
2   60    1   2.0 5.00
3   60    0   3.5 5.30
4   60    0   2.0 4.65
5   40    1   3.5 5.20
6   40    1   2.0 4.85
7   40    0   3.5 5.70
8   40    0   2.0 5.25
> is.matrix(zetam)
[1] TRUE
> is.data.frame(zetam)
[1] FALSE

Cheers
Petr

> a matrix. An important difference depending upon what you intend to do
> with the data.
> 
> However, in both cases, you can generally manipulate the data as if
> the headers were not present. In other words, most R functions will
> take the numeric values and act in a predictable (sorry for the pun)
> fashion. 
> 
> Think of the output above as if the column names X0 through X6 were A
> through G in a spreadsheet. They are simply labels, not part of the
> data itself. The same goes for the row names of 1 and 2.
> 
> HTH,
> 
> Marc Schwartz
> 
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Petr Pikal
petr.pikal at precheza.cz