[R] Panel plots for means of cyclical observations

[Richard M. Heiberger]

## Kieran,

## I think the root problem is that you allowed the levels of month to
be alphabetical.

## continuing with your example
##You need to take control of the levels with a statement like
levels(z$month)
z$month <- factor(z$month, levels=monthsOfYear)
levels(z$month)

## now you can write something like
z$month.parity <- factor(z$month,
levels=unlist(matrix(levels(z$month), 6, 2, byrow=TRUE)))
levels(z$month.parity)
##  [1] "January"   "March"     "May"       "July"      "September" "November"
##  [7] "February"  "April"     "June"      "August"    "October"   "December"
xyplot(rainfall ~ date | month, layout=c(2, 6), data=z)
xyplot(rainfall ~ date | month.parity, layout=c(6, 2), data=z)

## I hope the modifications to deal with your summary measures will be
straightforward.

## Rich


On Fri, Jan 15, 2016 at 7:16 AM, Kieran <kroberts012 at gmail.com> wrote:
> I want to create a panel plot using xyplot of a line graph whose
> x-axis is months of the year and y-axis is the average rainfall in a
> given month over the 6 years the data spans.
>
> There should be two levels in this panel plot: odd and even months.
>
> Creating this plot without splitting it into levels is quite
> straightforward (creating a for loop to compute a vector of averages)
> but the approach is not useful if you want to split the plots into
> different levels.
>
> Here is the code:
>
> dfmt <- "%d/%m/%Y"
> date <- seq(as.Date("01/01/2010", dfmt), as.Date("31/12/2015", dfmt),
>     "day")
> month <- months(date)
> rainfall <- runif(2191, 0, 150)
> monthsOfYear <- c("January", "February", "March", "April",
>     "May", "June", "July", "August", "September", "October",
>     "November", "December")
>
> parity <- match(month, monthsOfYear) %% 2
> # even parity = 0, odd parity = 1
>
> z <- data.frame(rainfall, date, month, parity)
>
> The problem with using xyplot( y ~ x | f, data=z .. ) is the x and y I
> want to plot are not columns in z but rather some kind of statistical
> summary of columns.
>
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