> First of all, thanks for all the replies!!
> What you have written helps, but is not entirely the answer to my problem.
>
> What I'd have is the creation of new data.frames each of one named with
> the ID of the original dataframe and with all the columns.
What was suggested gave you a list of data.frames, each named with the ID .
You can use the syntax list$name or list[["name"]] to refer to a data.frame.
R> splitData <- split(allData, allData$ID)
R> splitData$x1
ID value1 value2
1 x1 10 12
2 x1 12 22
3 x1 11 9
R> splitData$x2
ID value1 value2
4 x2 15 10
You seem to want a function that creates a bunch of data.frames in the
current environment instead of one that creates them in a list created to
hold them. This is not necessary and actually gets in the way most of the
time.
If you want to refer to 'x1' instead of 'splitData$x1' you can use 'with', as in
R> with(splitData, mean(x1$value2) - mean(x2$value2))
[1] 4.333333
instead of the slightly wordier
R> mean(splitData$x1$value2) - mean(splitData$x2$value2)
[1] 4.333333
If you want to process each sub-data.frame (these are data.frame, not matrices)
you can use lapply() or sapply() or vapply() on the list
R> dm <- sapply(splitData, function(x)mean(x$value2) - mean(x$value1))
R> dm
x1 x2 x3
3.333333 -5.000000 -2.500000
R> dm["x2"]
x2
-5
If you put all those names into the current environment you stand the chance
of clobbering some other dataset whose name matched one of the entries in
allData$ID. Also you would have to use some rather ugly code involving get()
and assign() to manipulate the objects. Learn to love lists.
Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com
> -----Original Message-----
> From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On
> Behalf
> Of matteo
> Sent: Monday, June 24, 2013 11:32 AM
> To: Bert Gunter
> Cc: r-help@r-project.org
> Subject: Re: [R] extracting submatrix from a bigger one
>
> First of all, thanks for all the replies!!
> What you have written helps, but is not entirely the answer to my problem.
>
> What I'd have is the creation of new data.frames each of one named with
> the ID of the original dataframe and with all the columns.
>
> For example, in the original dataframe one column (ID) has 5 different
> elements:
>
> ID value1 value2
> x1 10 12
> x1 12 22
> x1 11 9
> x2 15 10
> x3 11 11
> x3 13 8
>
> I need a command ables to split the dataframe in other smallest and
> separated dataframes, so that they look like
>
> x1 is
> ID value1 value2
> x1 10 12
> x1 12 22
> x1 11 9
>
> x2 is
> ID value1 value2
> x2 15 10
>
> and x3 is
> ID value1 value2
> x1 10 12
> x3 11 11
> x3 13 8
>
>
> Sorry if I'm not able to explain it better and as I said I'm very new to
> R.....
>
> Thanks
>
> Matteo
>
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> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
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