[R] loading multiple .Rdata and preserving variable names

[Duncan Murdoch]

On 15/07/2009 5:00 AM, Žroutík wrote:
> Dear R-users,
> 
> I need to load outputs from multiple previous calculations into one R
> session for comparison and (cross-)analysis. The previous calculations are
> stored in different directories in .Rdata files (I don't know if this is the
> best storage for later usage, but the previous project could be recalculated
> and saved into different format, if needed, potentially.)
> 
> I can load consequently multiple .Rdata files (in which variable names are
> identical), but I don't know how to preserve variables from these files or
> make them unique.
> 
> I would imagine pointing them as in a list:
> 
> # loading 2, max. 4 outputs of previous calculations
> load(DataSet1) # VariableA is present
> load(DataSet2) # VariableA is present, too
> 
> # both VraiableA listed and present
> DataSet1$VariableA$parameters
> DataSet2$VariableA$parameters
> 
> But what is the way to feed all variables into a list? Or more generally,
> what is an efficient way to work with multiple separate outputs which one
> would like to compare?
> 
> (I have read something about environments, but I understood it's only for
> functions. I could create environments, but was not succesful in using them
> at all (location change or separate sandbox). Functions saveCache,
> loadCache, saveObject, loadObject is not really what I have in mind, too --
> saveObject(list=ls(), "NewObjectFile") is not a solution either...)

Environments are basic in R.  If they are "only for functions", it's 
because everything in R is done by functions.

Given two .RData files, you can load them into separate environments. 
Dealing with conflicting variables names is another issue, of course.

For example:

DataSet1 <- new.env()
load( "somefile", envir=DataSet1)

Now use ls(DataSet1) to see what you've got, repeat for DataSet2, etc. 
You can get a variable as DataSet1$VariableA.

Duncan Murdoch

> 
> Thanks for any hint in advance.
> 
> Cheers, Zroutik
> 
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