Re: [R] Dating Objects

From: Paul Gilbert <>
Date: Sat 13 Aug 2005 - 07:27:31 EST

Barry Rowlingson wrote:

> Rolf Turner wrote:

>>	I don't follow what you aren't following ....  It seems to me
>>	to be an eminently reasonable thing to want to do.  Answers
>>	questions such as ``Was x modified since y was modified?''

> I wanted to have some sort of 'make'-like functionality in R.

Why not just use make and generate a sequence of targets that come from renaming the .RData file saved after each step.

> you have some complicated analysis that depends on several variables. If
> you change one of them, you might not want to redo all the parts of the
> analyses that dont depend on that change. Integrating this with Sweave
> would be another gem, since parts of your Sweave document that might
> take a long time to run might not need to run again if you've only
> changed something after that point. If it takes an hour to generate a
> dataset and two seconds to plot it, and you've made a change to the
> plot, you dont want to re-run the whole data generation again when you
> weave your document.

>>	I think I would make the modification data an ***attribute***
>>	of the object, rather than sticking it in as a component.
>>	(The latter might mess up some vital aspect of the nature
>>	of the object.)
>>	The problem is to remember to date stamp each object each
>>	time it is modified ....

> A while ago I attacked this problem at the C-code level. I found out
> where R made assignments and tacked on a 'modified' attribute to the
> object at that point. However it was a quick hack and it broke R quite
> badly. One of the problems was that R objects were no longer identical
> to assigned versions of themselves, and lots of tests broke.
> I think to be done properly it needs to be done at a lower level.

Well, I guess what I'm suggesting is at a much higher level.

> Barry
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> PLEASE do read the posting guide! mailing list PLEASE do read the posting guide! Received on Sat Aug 13 07:37:10 2005

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