[R] Results of applying na.omit on zoo object

[Gabor Grothendieck]

On Mon, Sep 19, 2011 at 7:52 PM, Marc Schwartz <marc_schwartz at me.com> wrote:
> Hi Rich,
>
> On Sep 19, 2011, at 5:18 PM, Rich Shepard wrote:
>
>> On Mon, 19 Sep 2011, Marc Schwartz wrote:
>>
>>> 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.
>>
>> Marc,
>>
>>  A lot of folks on the mail list here seem to be in the medical side of
>> biology. I'm a stream ecologist/fluvial geomorphologist with 30 or so years
>> of professional experience and each project seems to need new software and
>> increases in my knowledge to address. I now have two projects involving
>> water quality that will involve integration of time series analyses,
>> regression analyses, and spatial modeling of terrain and hydrology. The last
>> component I've used frequently the past decade or so, the advanced data
>> analyses and statistical modeling has come up only now.
>>
>>> 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.
>>
>>  Yes, I can specify the start and end dates using as.Date.
>
> As I noted in my reply to Gabor just now, just be aware of the difference between zoo's as.Date() function, which masks base R's function of the same name, which also has an 'origin' argument.

If you are using zoo whether or not you use as.Date's
origin="1970-01-01" argument it won't matter. It will work and give
the same answer in both cases so there is really no good reason to be
particularly aware of this.  You can't easily go wrong.

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