R help - May 2012 - linear extrapolation using data from imported text file

Dear?R experts,
?
I?am trying to do linear extrapolation on a dataset?like the attached document.
I looked at the approx and approxfun function that seem to do this function, but
not fully understand them. I was wondering if someone could help with writing
commands to do the following based on the attached file's example:
?
ID#1 and ID?#2 both have response parameters ("MEASUREMENT" in the
Book1.txt file) for a given time point ("TIME (hours)" in the
Book1.txt file). Using linear extrapolation?I would like to be able to compute
the percent time spent in the "MEASUREMENT" range of 9 to 10, for
ID#1?and ID#2, together and?individually.??
?
in the attached simple example, if I did the calculation then the results
would?be:
?
1;? 66% for ID #1 and 100% for ID#2, individually. This is the 1st value I would
like to compute
?
2; Combined together?the results would be the average of 66% and 100%, which
equals to ?83%, This is the?2nd value I would like to compute
?
all of your help is apreciated,
?
thanks,
?
Andras
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