[R] Interpolating a line and then summing there values for a diurnal oxygen curve (zoo object)

[Gabor Grothendieck]

Try this using your z and library(zoo):

# extract section of interest
w <- window(z, start=chron("6/8/6", "4:16:0"), end=chron("6/8/6", "20:31:0"))

# zap all interior points with NA's and then fill back in using linear
interpolation
lin <- na.approx(replace(w, time(w) > start(w) & time(w) < end(w), NA))

# plot the 3 series on one screen
plot(merge(z, w, lin), col = 1:3, screen = 1)


On Sun, Jul 27, 2008 at 8:12 PM, stephen sefick <ssefick at gmail.com> wrote:
> #I would like to interpolate a straight line between 06/08/06  04:16:00 -
> 06/08/06 20:31:00 with values and then sum them.  This is an estimate of
> ecosystem #respiration and I will be using this in a larger context(48 days
> of these diurnal curves), but for right now I am just trying to figure out
> how to do it for this one #day example.  I have some other code for
> Ecosystem (stream) Metabolism that I am trying to work up into a package,
> but I am still assembling the pieces.
> #thanks for all of your help
>
> library(chron)
> library(zoo)
> z <- structure(c(7.7, 7.7, 7.7, 7.7, 7.7, 7.71, 7.7, 7.71, 7.71, 7.7,
> 7.7, 7.7, 7.7, 7.69, 7.68, 7.68, 7.67, 7.67, 7.67, 7.66, 7.65,
> 7.65, 7.65, 7.64, 7.64, 7.63, 7.63, 7.63, 7.62, 7.62, 7.62, 7.62,
> 7.63, 7.63, 7.63, 7.63, 7.63, 7.64, 7.64, 7.65, 7.65, 7.65, 7.66,
> 7.66, 7.67, 7.67, 7.67, 7.68, 7.68, 7.69, 7.69, 7.69, 7.69, 7.7,
> 7.7, 7.7, 7.7, 7.7, 7.71, 7.7, 7.7, 7.71, 7.71, 7.7, 7.7, 7.7,
> 7.7, 7.7, 7.7, 7.7, 7.69, 7.68, 7.68, 7.68, 7.67, 7.67, 7.66,
> 7.66, 7.66, 7.66, 7.65, 7.65, 7.65, 7.65, 7.66, 7.66, 7.66, 7.67,
> 7.67, 7.68, 7.68, 7.68, 7.68, 7.69, 7.69, 7.69), index =
> structure(c(13307.0006944444,
> 13307.0111111111, 13307.0215277778, 13307.0319444444, 13307.0423611111,
> 13307.0527777778, 13307.0631944444, 13307.0736111111, 13307.0840277778,
> 13307.0944444444, 13307.1048611111, 13307.1152777778, 13307.1256944444,
> 13307.1361111111, 13307.1465277778, 13307.1569444444, 13307.1673611111,
> 13307.1777777778, 13307.1881944444, 13307.1986111111, 13307.2090277778,
> 13307.2194444444, 13307.2298611111, 13307.2402777778, 13307.2506944444,
> 13307.2611111111, 13307.2715277778, 13307.2819444444, 13307.2923611111,
> 13307.3027777778, 13307.3131944444, 13307.3236111111, 13307.3340277778,
> 13307.3444444444, 13307.3548611111, 13307.3652777778, 13307.3756944444,
> 13307.3861111111, 13307.3965277778, 13307.4069444444, 13307.4173611111,
> 13307.4277777778, 13307.4381944444, 13307.4486111111, 13307.4590277778,
> 13307.4694444444, 13307.4798611111, 13307.4902777778, 13307.5006944444,
> 13307.5111111111, 13307.5215277778, 13307.5319444444, 13307.5423611111,
> 13307.5527777778, 13307.5631944444, 13307.5736111111, 13307.5840277778,
> 13307.5944444444, 13307.6048611111, 13307.6152777778, 13307.6256944444,
> 13307.6361111111, 13307.6465277778, 13307.6569444444, 13307.6673611111,
> 13307.6777777778, 13307.6881944444, 13307.6986111111, 13307.7090277778,
> 13307.7194444444, 13307.7298611111, 13307.7402777778, 13307.7506944444,
> 13307.7611111111, 13307.7715277778, 13307.7819444444, 13307.7923611111,
> 13307.8027777778, 13307.8131944444, 13307.8236111111, 13307.8340277778,
> 13307.8444444444, 13307.8548611111, 13307.8652777778, 13307.8756944444,
> 13307.8861111111, 13307.8965277778, 13307.9069444444, 13307.9173611111,
> 13307.9277777778, 13307.9381944444, 13307.9486111111, 13307.9590277778,
> 13307.9694444444, 13307.9798611111, 13307.9902777778), format =
> structure(c("m/d/y",
> "h:m:s"), .Names = c("dates", "times")), origin = structure(c(1,
> 1, 1970), .Names = c("month", "day", "year")), class = c("chron",
> "dates", "times")), class = "zoo")
> plot(z)
>
> --
> Let's not spend our time and resources thinking about things that are so
> little or so large that all they really do for us is puff us up and make us
> feel like gods. We are mammals, and have not exhausted the annoying little
> problems of being mammals.
>
> -K. Mullis
>
>        [[alternative HTML version deleted]]
>
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