[Rd] manage R function and data dependencies like 'make'

[Paul Gilbert]

I use make to do things like you describe. Here is an example target 
from one of my Makerules files:

$(T:%=compare.R$(REP).T%):compare.%: compare.R estimates.%
	@echo making $(notdir $(PWD)) $@ because $? changed ...
	@(cd  $(subst compare.,,$@) ; \
	    echo "z <- try( source('../compare.R')); \
	  if (!inherits(z, 'try-error')) q('yes', status=0) else \
	   {print(z); q('yes', status=1)} "  | \
	      R --slave >../$(FLAGS)/$@.log 2>&1)
	@mv $(FLAGS)/$@.log $(FLAGS)/$@


I realize this is out of context and possibly mangled by mail wrap, but 
if you are familiar with (GNU) make then it should give you a good idea 
what to do. In this example I am accumulating (intermediate) things in 
the .RData file and using flags as targets to indicate the status of 
different steps. Another possibility would be to rename the .RData files 
and use them as the targets. Let me know if you want a more complete 
example.

I really would encourage you to think of wrapping R (like a compiler) in 
make, rather than trying to re-implement something like make within R.

(I would be interested to see examples if anyone is using Ant to do this 
kind of thing.)

Paul


Lutz Prechelt wrote:
> Dear R-devels,
> 
> I am looking for a package (or some other infrastructure) for the
> following situation:
> 
> I am doing a larger data evaluation.
> I have several dozen data files and do not want to keep the persistent
> data in the R workspace (for robustness reasons).
> I have several dozen R files, some for reading and preprocessing data
> files, others for doing plots or analyses.
> I will make frequent changes to both data files and R files while doing
> the analysis.
> 
> I would like to automate mechanisms that allow 
> - a data file reading function to suppress its actual work if neither
> the data file nor the R file containing the function were modified since
> the data file was last read
> - an R file sourcing function to suppress its actual work if the R file
> has not been modified
> - and perhaps even: automate re-reading a data file upon access to the
> corresponding dataframe iff the file has been modified since the
> dataframe was created.
> 
> In short: Something like Unix's 'make', but for managing dependencies of
> functions and dataframes in addition to files. In R. (And of course I am
> very open for solutions that are more elegant than what I have sketched
> above.)
> 
> I could not find something in the help and have rather few ideas for
> good search terms.
> 
> I any such thing available?
> (If no such infrastructure exists, what is the right R function for
> accessing file modification dates?)
> 
> Thanks!
> 
>   Lutz
> 
> ______________________________________________
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> https://stat.ethz.ch/mailman/listinfo/r-devel
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