On Mon, Sep 19, 2011 at 5:24 PM, Rich Shepard <rshep...@appl-ecosys.com> wrote:
> On Mon, 19 Sep 2011, Rich Shepard wrote:
>
>> On a related note, I'm reading the zoo help pages and vignettes but do
>> not see the syntax for specifying which stream/parameter pair I want to
>> plot. What do I read to learn how to do this?
>
> I think that my reading answered this question, but now I need to refine
> the plots.
>
> If I run 'plot(z[, 1])' for example I get the stream/parameter pair in
> that is on the left of the top row. This leads to two refinement questions:
>
> 1) How can I get a list of the stream/parameter pairs and their position
> in the summary matrix? and,
names(z) gives the column names of zoo object z. If the third column
is named SO then z[, 3], z[, "SO"] or z$SO will give that single
column.
>
> 2) How can I determine the earliest and latest dates in each
> stream/parameter pair in which there are data? According to the zoo.quickref
> vignette, start and end provide the earliest and last dates in the index,
> not necessarily for a specific stream/paramater pair. Once I have those
> dates I can specify start = as.Date("<start-date>") and end =
> as.Date("<end-date>")
library(zoo)
# test data
z <- zoo(cbind(a = c(NA, 1:3, NA), b = c(NA, NA, 1:3)), Sys.Date() + 1:5)
# get a list of date ranges
lapply(1:ncol(z), function(i) range(time(na.omit(z[, i]))))
which gives:
[[1]]
[1] "2011-09-21" "2011-09-23"
[[2]]
[1] "2011-09-22" "2011-09-24"
--
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