image.seas.sum {seas}

Show a seasonal sum data object

Description

Graphically display a seasonal sum object, as well as the method of solution of the median/quantile “normal”

Usage

## S3 method for class 'seas.sum'
image(x, var, norm = "days", start = 1, rep = 0, zlim, alim,
    palette = colorRampPalette(c("white", "blue"))(64),
    year.filter, power, contour = TRUE, show.median, main, ...)

Arguments

x

a seas.sum object

var

the desired variable to show, otherwise will use the prime variable, defined in x

norm

variable to normalize by, usually "days", to produce unit/day

start

starting bin number; e.g., for monthly sums, if start=5, the plot will start on "May" at the left-hand side; show.median cannot be produced if start is greater than one, since the annual sums (row-wise) would be a mix of different annums

rep

repetition of the bins (columns)

zlim

range of normalized values displayed; this can be either a single number for the maximum (minimum set to zero), or a c(min, max) range with a defined minimum

alim

if show.median, this is the range for the annual sums; this can either be a singe number for the maximum (minimum set to zero, or a c(min, max) range with a defined minimum

palette

colours for image; the use of colorRampPalette is recommended

year.filter

specifies the annual seasons to display

power

this transforms the normalized values for the colours to a power (^), such as 0.5 for square-root (sqrt), or others; this can help improve the contrast in the display of data, but the quantities displayed in the colour-bar and contours remain untransformed

contour

logical; show contours in lower left-hand plot

show.median

logical; show how the median calculation is achieved graphically (computationally it is done using a secant method); see seas.norm for more information on this method; this can only be shown if the annums (rows) are complete, so start must be 1, and rep must be 0 (otherwise the row-wise sums would not be the annual sums)

main

main title for plot, otherwise it will automatically be generated; NA suppresses a title, and automatically adjusts the device margins

...

ignored

Details

This is a graphical representation of a seas.sum object, and is far more informative than a traditional precipitation “normal” (i.e., precip.norm or precip.norm)

If norm = "days" and show.median = TRUE (default), the seasonal sums appear in right-hand frames. Horizontal and vertical lines indicate a ‘normal’ from the image, whereby the sum of the quantile is equal to the median of the annual amount. This numerical solution is found using seas.norm.

Author(s)

Mike Toews

See Also

seas.sum, seas.norm

See SeasOpts to modify other aspects of the plot

Examples

data(mscdata)
dat <- mksub(mscdata, id=1108447)

dat.ss <- seas.sum(dat, width="mon")
image(dat.ss)

image(dat.ss, contour=FALSE)

image(dat.ss, norm="active", start=6, rep=5)

# different start day (not Jan 1st)
dat2.ss <- seas.sum(dat, start.day=as.Date("2001-08-01"))
image(dat2.ss)
image(dat2.ss, power=2)
image(dat2.ss, palette=rainbow(64), main=NA)  # no title
image(dat2.ss, palette=colorRampPalette(c("white", "darkgreen"))(16))
image(dat2.ss, "snow")
image(dat2.ss, "snow", power=0.5)

# growing degree days for 10 degC
dat$gdd10 <- dat$t_mean - 10
dat$gdd10[dat$gdd10 < 0] <- 0
attr(dat$gdd10,"long.name") <- "growing degree days"
dat3.ss <- seas.sum(dat, var="gdd10")
image(dat3.ss, "gdd10", palette=colorRampPalette(c("white", "red"))(64))