[R] time series with quality codes

[Felix Andrews]

list(...),

I am working with environmental time series (eg rainfall, stream flow)
that have attached quality codes for each data point. The quality
codes have just a few factor levels, like "good", "suspect", "poor",
"imputed". I use the quality codes in plots and summaries. They are
carried through when a time series is aggregated to a longer
time-step, according to rules like "worst", "median" or "mode".

I need to support time steps of anything from hours to years. I can
assume the data are regular time series -- they might be irregular
initially but could be 'regularized'. But I would want to plot
irregular time series along with regular ones.

So far I have been using a data frame with a POSIXct column, a numeric
column and a factor column. However I would like to use zoo instead,
because of its many utility functions and easy conversion to ts. Is
there any prospect of zoo handling such numeric + factor data? Other
suggestions on elegant ways to do it are also welcome.

Felix

-- 
Felix Andrews / 安福立
PhD candidate
Integrated Catchment Assessment and Management Centre
The Fenner School of Environment and Society
The Australian National University (Building 48A), ACT 0200
Beijing Bag, Locked Bag 40, Kingston ACT 2604
http://www.neurofractal.org/felix/
xmpp:foolish.android at gmail.com
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