[R] Plotting Questions (was: Results of applying na.omit on zoo object)

[Gabor Grothendieck]

On Mon, Sep 19, 2011 at 5:24 PM, Rich Shepard <rshepard at 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"


-- 
Statistics & Software Consulting
GKX Group, GKX Associates Inc.
tel: 1-877-GKX-GROUP
email: ggrothendieck at gmail.com