On Jul 22, 2011, at 7:01 PM, Derrick Lin wrote:
Hi R-help,
I have a dataframe consisting of a time-series [t, v]. The
timestamps aren't
at all evenly spaced. The values are continuous. I've been able to
graph
this as a step function (which is what it should be) in ggplot2,
using the
'step' geom. Now I would like to take the integral of the step
function.
For this and other reasons, is there a way to convert this into an
evenly
time-interval-ed array?
If you had provided reproducible code there might have been more
response. Since you have the data in a dataset it would have been no
trouble at all to just post dput() applied to the example. Instead,
here you are 3 days later with no reply.
example current dataframe:
t(currently as.POSIXct-ed) value
5/31/11 0:00 7.56
5/31/11 0:01 7.78
5/31/11 1:05 3.00
5/31/11 1:17 8.32
desired (something like this, anyway):
t value
5/31/11 0:00 7.56
5/31/11 0:05 7.78
5/31/11 0:10 7.78
... ...
5/31/11 1:00 7.78
5/31/11 1:05 3.00
5/31/11 1:10 3.00
5/31/11 1:15 3.00
5/31/11 1:20 8.32
I would have been converting this example to a zoo object and then
merging with a dataset whose range matched yours but that was on a one
minute timescale. You could then use the locf interpolation option
that the zoo functions support and then pickout the 5 minute values
after the interpolation/
--
David.
It could also be factors like: 0:00 - 0:05, 7.56. However I don't
think my
grasp of this is very good. It'd also be great if the solution were
general
purpose so that I can change the parameters as needed (like interval
size).
I've been banging my head on #R and begun reading plyr/reshape
documentation, so I would really appreciate any help!
-Derrick
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David Winsemius, MD
West Hartford, CT
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