On Sep 19, 2011, at 5:06 PM, Gabor Grothendieck wrote:
> On Mon, Sep 19, 2011 at 5:33 PM, Marc Schwartz <[email protected]> wrote:
>> On Sep 19, 2011, at 4:00 PM, Rich Shepard wrote:
>>
>>> On Mon, 19 Sep 2011, Marc Schwartz wrote:
>>>
>>>>> Is there a way to omit only those rows where all columns contain 'NA'?
>>>
>>>> You can look at ?complete.cases for one approach, presuming that it will
>>>> work on zoo objects.
>>>
>>> Marc,
>>>
>>> Do I even need to worry about these NAs? Thanks to Gabor I have a data
>>> frame with 296 stream/parameter sets. Each set begins and ends on a
>>> different date (used as the zoo index).
>>>
>>> What I want to do initially is plot the time series for each
>>> stream/parameter to see what each has to tell us. In this case, if there are
>>> years of NAs prior to the fist measurement for that stream/parameter pair,
>>> will this affect anything.
>>>
>>> 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?
>>>
>>> Rich
>>
>>
>> Hi Rich,
>>
>> Let me start by acknowledging that I have little practical experience in
>> time series analyses, much less proficiency with the zoo package. I just
>> don't come across them much in clinical trials/studies, at least the ones
>> that I have been involved with over the past 25+ years.
>>
>> I do know from prior posts on the matter, that the zoo package seems to have
>> some of its own approaches to dealing with dates, as compared to base R. So
>> you may need to be clear on the differentiation in code/functions required
>> to use some of the package functionality.
>
> This is not at all the case. zoo relies on external facilities to
> handle index classes and not its own facilities.
>
> In some cases zoo extends base facilities or adds new classes to give
> additional possibilities but when this is done the base functionality
> is always extended and never changed. There are no exceptions to this
> rule.
My apologies then Gabor for perhaps over-generalizing. As noted, I do not use
zoo, but of course have seen posts previously regarding the conflicts between
R's as.Date() function and zoo's function of the same name, due to the
presence/absence of the 'origin' argument. I was not sure if there may be
others. Thanks for the clarification.
Regards,
Marc
>
> In fact, the only time zoo functions or methods have any understanding
> of index classes is when interfacing to the outside world since such
> interfacing implies knowledge of how the external objects work.
>
> For accurate information on the design of zoo read
>
> vignette("zoo-design")
>
> and the other four vignettes and as well as the help files in the zoo package.
>
> Regarding plotting plotting in zoo is similar to in R so NAs are
> ignored in plots. Thus leading and trailing NAs do not result in
> anything on the plot. To plot a zoo object try:
>
> plot(z) # multiple panels
> plot(z, screen = 1) # all columns on 1 panel
>
> or
>
> library(lattice)
> xyplot(z)
>
> xyplot also accepts the screen= argument and more info is in ?plot.zoo
> and ?xyplot.zoo Like most zoo functions they tend to work like core
> R functions so if you understand those then the working with the zoo
> ones come natural.
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