[R] Polar graph of time and tide
ggrothendieck at gmail.com
Wed May 2 15:57:24 CEST 2007
On 5/2/07, Jim Lemon <jim at bitwrit.com.au> wrote:
> Alan E. Davis wrote:
> > I have been trying to visualize times of lowest tides, month by month.
> > I have tide predictions with times either in unix time or a text
> > format, and heights in feet or meters. I had been able to derive the
> > clock times of each prediction. I would now like to graph this data
> > with points showing heights as "r" and times as "theta", from 0000 to
> > 2355. There is a seasonal component: I am interested in displaying
> > times of lowest tides in particular.
> > I am sure this is so simple as to burden those on the list; I however
> > have spent two evenings trying to figure out how to use polar.plot,
> > and I'm not sure that's the best way to do this. May I request some
> > advice? The docs with polar.plot are not complete, I fear.
> > Thank you, begging for your indulgence,
> Hi Alan,
> Earl Glynn's advice is spot-on if you are trying to map tides onto the
> diurnal cycle. However, I get the impression that you want an annual
> cycle. If this is the case, it is probably best to go to the underlying
> function, radial.plot. Here is an example with some imaginary tides.
Note that month.abb is built into R so one could eliminate the
month.abbr<- line and write:
radial.plot(lowtide, labels = month.abb, rp.type = "s")
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