[R] Calculate area under a curve

[Greg Snow]

The mean values theorem of integration (which I think typifies the differences in thinking between mathematicians and statisticians) says that the integral from a to b is equal to the average value of the curve between a and b times the distance from a to b (b - a).

I would be interested in how similar the areas computed using the other methods suggested compare to just averaging your data and multiplying by the distance.

-- 
Gregory (Greg) L. Snow Ph.D.
Statistical Data Center
Intermountain Healthcare
greg.snow at imail.org
801.408.8111


> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of suse
> Sent: Thursday, July 01, 2010 8:57 AM
> To: r-help at r-project.org
> Subject: [R] Calculate area under a curve
> 
> 
> Hi,
> 
> I want to know the area under a curve, which is not given as a
> function, but
> as values in a time series. It is  not a smooth curve, but switches
> often
> between positive values and zero (the values describe the moisture in
> the
> soil over a year, one entry is one day). I already tried
> area.between.curves, but got only 0 as result. I guess, it doesn't work
> because of these multiple changes between 0 and positive values (most
> of the
> time, the values are 0 and in the certain case I tested, the positive
> values
> were only on single days; but for other values positive values last
> longer)
> I hope, someone can help me!
> 
> THank you!
> --
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> area-under-a-curve-tp2275283p2275283.html
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