On Wed, 15 Jul 2009, Liviu Andronic wrote:
Hello Patrick,
On 7/15/09, Patrick Burns <pbu...@pburns.seanet.com> wrote:
How about something along the lines of:
apply(twocolumns, 1, any)
This efficiently solves the first part of my question. I will probably
content myself with issuing this command each time I update one of the
"twocolumns"; I'm still curious whether R can store this function in
the third column, and autoupdate it whenever one of the "twocolumns"
gets modified (behaviour very similar to that of spreadsheets),
although I'd doubt R could.
Well, I am 'thinking out loud' here, so you've been warned...
The open.account() example in Intro to R 10.7 shows how you might do
updates in a very structured (and limited) way. You specify how all the
updates are done (e.g. of 'total' in that example) in advance of creating
any objects and keep the objects in an environment whose objects are only
modified thru a function along the lines of open.account().
---
Another approach is to define a class 'revised-by-another' (say) that
marks objects that may be modified by changes in other objects and another
class 'revises-another' that marks objects upon which some
'revised-by-another' object depends. When '[.revises.another' or
'[[.revises.another' is called, a search is triggered for objects
inheriting 'revised-by-another' and a graph of revisions is defined and
then executed. That graph would need to account for dependencies in which
a change in X3 changes X2 and X1, but X1 explicitly depends on both X2 and
X3 (so X2 needs to be modified before X1).
---
Another (related) approach would use the 'make' utility to manage updates
and construct the graph mentioned in the previous paragraph. I vaguely
recall seeing something about this - maybe a package - but I cannot lay my
hands on it. (Then, too, there is 'weaver' on bioconductor that provides
some related functionality.)
HTH,
Chuck
>
Thank you
Liviu
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Charles C. Berry (858) 534-2098
Dept of Family/Preventive Medicine
E mailto:cbe...@tajo.ucsd.edu UC San Diego
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