[R] x y averaging

[Gabor Grothendieck]

Modifying the invalid times 14:62:11 and 14:68:11 to other values
try the following:


Lines1 <- "x y
14:56:10  0.325
14:57:11  0.111
14:58:11  0.214
16:05:18  0.245
16:11:09  0.266
16:17:05  0.271
16:33:00  0.304
16:39:05  0.300"

Lines2 <- "x y
15:59:08  0.255
16:05:44  0.281
16:11:25  0.249
16:17:39  0.238
16:23:51  0.288"

library(zoo)
library(chron)
z1 <- read.zoo(textConnection(Lines1), header = TRUE, FUN = times)
z2 <- read.zoo(textConnection(Lines2), header = TRUE, FUN = times)
z <- merge(z1, z2)  # use merge(z1, z2, ..., zn) if you have n of these
zoo(rowMeans(z, na.rm = TRUE), time(z))


On 6/6/06, Randy Zelick <zelickr at pdx.edu> wrote:
> Hello,
>
> I am trying to average a number of data sets where the x vector contains
> times and the Y data are instrument readings. The vectors all have
> different numbers of values, but many X time values match. For example:
>
> A fragment of the first data set:
>
> x vect    value
> 14:56:10  0.325
> 14:62:11  0.111
> 14:68:11  0.214
> .
> .
> .
> this can go on for 100's of values, spaced by 6 minutes, but there can be
> gaps too, like:
>
> 16:05:18  0.245
> 16:11:09  0.266
> 16:17:05  0.271
> 16:33:00  0.304
> 16:39:05  0.300
>
>
> A fragment of the second data set:
>
> 15:59:08  0.255
> 16:05:44  0.281
> 16:11:25  0.249
> 16:17:39  0.238
> 16:23:51  0.288
>
>
> ...and the result I am looking for is a new vector that looks like this:
>
> 14:56:10  0.325
> 14:62:11  0.111
> 14:68:11  0.214
> .
> .
> .
> 15:59:08  0.255
> 16:05:18  0.2630  * matches, so average
> 16:11:09  0.2575  * matches, so average
> 16:17:05  0.2545  * matches, so average
> 16:33:00  0.304
> 16:39:05  0.300
>
>
> The times values in the new X vector are properly interleaved taking data
> across the datasets, but when there is a match the Y values are averaged.
> Note that the seconds don't matter.
>
> I am using R Version 2.2.1 on a PC
>
> Thanks for thinking about it,
>
> =Randy=
>
> R. Zelick                               email: zelickr at pdx.edu
> Department of Biology                   voice: 503-725-3086
> Portland State University               fax:   503-725-3888
>
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>
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