[R] plotting the one-dimensional density of events in time

[William Dunlap]

You could change the x component of density's output back into a Date object
and let plot choose a Date axis in its usual way.  E.g.,
  > den <- density(as.numeric(dd))
  > den$x <- as.Date(den$x, origin=as.Date("1970-01-01"))
  > plot(den$x, den$y)
(You probably will also want to normalize the y component to be on a
specific
per time unit, say day or year, basis.)



Bill Dunlap
TIBCO Software
wdunlap tibco.com

On Fri, Mar 6, 2015 at 1:03 PM, Christopher W. Ryan <cryan at binghamton.edu>
wrote:

> I have the dates of occurence of a repetitive event. I would like to
> plot the density of these events, as well as their specific temporal
> location.  This is as far as I have gotten:
>
> # generate some sample data: dates in 2014
> random.dates <- sample(1:31, 100, replace=TRUE)
> random.months <- sample(1:12, 100, replace=TRUE)
> dd <- as.Date(as.character((paste(random.dates, random.months, "2014",
> sep="-"))), format="%d-%m-%Y")
> dd <- dd[!is.na(dd)]
>
> # plot density with a "rug".
> density(as.numeric(dd))
> plot(density(as.numeric(dd)))
> rug(as.numeric(dd))
>
> # But horizontal axis label is not very informative
> # would prefer labeling the start of each month
> plot(density(as.numeric(dd)), axes=FALSE)
> library(zoo)
> new.axis <- as.yearmon(dd)
>
> # but then what? This is where I get stuck--adding back a sensible axis
>
> Grateful for any guidance.
>
> Thanks.
>
> --Chris
> --
> Christopher W. Ryan, MD, MS
> cryanatbinghamtondotedu
>
> Early success is a terrible teacher. You’re essentially being rewarded
> for a lack of preparation, so when you find yourself in a situation
> where you must prepare, you can’t do it. You don’t know how.
> --Chris Hadfield, An Astronaut's Guide to Life on Earth
>
>
> ---
>
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