[R] reading of a matrix

[Charilaos Skiadas]

On Apr 5, 2007, at 6:50 AM, Schmitt, Corinna wrote:

> Dear R-experts,
>
> I still have problems with the reading of a matrix.
>
> Input: matrixData6.txt
>
> A-Paar B-Paar C-Paar D-Paar E-Paar
> A 1  3  5  7  9
> B 2  4  6  8 10
>
>
> R-commands:
> y=read.table(file="Z:/Software/R-Programme/matrixData6.txt")
> y
>
> Result:
>   A.Paar B.Paar C.Paar D.Paar E.Paar
> A      1      3      5      7      9
> B      2      4      6      8     10
>
>
> If you look into the txt-file you can recognize that the column names
> are not the same. Why?
>
Look at ?read.table for details, basically the variable names are  
turned into syntactically valid names via make.names (?make.names).  
This is, I pressume, so that you can later refer to them via: df 
$A.Paar  (df$A-Paar means something very different). You can try to  
add: check.names=FALSE to the read.table call, not sure it will do  
what you want it to.

> If I add in the txt-file the line "MyData:" infront of all followed  
> by a
> newline. The R-command as above response an error. How can I read the
> modified input and get the following result:

Hm, if you really want the MyData to show up in the result, then you  
will have to do some more hard work, since data frames don't really  
have a room for that. But if you simply want MyData: to show up in  
the text file but not be read by R, then you would want to prepend  
the line with the comment character, #.

> MyData:
>
>    A.Paar B.Paar C.Paar D.Paar E.Paar
> A      1      3      5      7      9
> B      2      4      6      8     10
>
> Another stupid question might be hows can I change the column and row
> names after I made "read.table"? I want to have the following result,
> for example:
>
names(yourdf) <- c("G","H","I","J","K")
or perhaps better:
names(yourdf) <- LETTERS[6+1:5]

That's for the columns. Use ?rownames for the rows.
> MyData:
>
>        G      H      I      J      K
> M      1      3      5      7      9
> N      2      4      6      8     10
>
> I studied all manuals I could find and the help but could not  
> understand
> the examples or interpret it right for my case.
>
> Thanks for help,
>
> Corinna
>
Haris Skiadas
Department of Mathematics and Computer Science
Hanover College