circular (version 0.3-1)

windrose: Windrose Generator

Description

This function creates a windrose used to visualize the direction and magnitude of wind. The pedals of a windrose indicate the proportion of time wind comes from a given direction. Bands on the windrose indicate the proportions of winds of each magnitude.

Usage

windrose(x, y=NULL, breaks=NULL, bins=12, increment = 10, main='Wind Rose', cir.ind = 0.05, fill.col=NULL, plot.mids=TRUE, mids.size=1.2, osize=0.1, axes=TRUE, ticks=TRUE, tcl=0.025, tcl.text=-0.15, cex = 1, digits=2, num.ticks=12, xlim=c(-1.2, 1.2), ylim=c(-1.2, 1.2), uin, tol=0.04, right=FALSE, shrink=NULL, ...)

Arguments

x

a vector contains direction or a two columns data frame, where the first component is the direction and the second the magnitude. The vector or the first column in the case of data frame is coerced to class circular

y

a vector contains magnitude. If 'y' is not NULL and 'x' is a dataframe, only the first column of 'x' is used for direction.

breaks

the extremes of the pedals. The biggest value (in 2*pi) is recycled for building the first pedal. The vector is coerced to class circular but only the units is used.

bins

Number of pedals. Ignored if 'breaks' is not NULL.

increment

Grouping size of magnitude. These are the bins of the magnitudes displayed on each pedal.

main

Title for plot.

cir.ind

Percent intervals expressed on each circle if the pedals are equally spaced, otherwise values of density

fill.col

colors used to fill the pedals for each magnitude. The colors are recycled if necessary. The default is to use 'blue' and 'red'.

plot.mids

plot lines at the midpoints of the pedals.

mids.size

length of the lines for midpoints.

osize

radius of the circle draws at the center of the plot.

axes

if TRUE axes are added to the plot. The function axis.circular is used.

ticks

if TRUE ticks are added to the plot. The function ticks.circular is used.

tcl

length of the ticks.

tcl.text

The position of the axis labels.

cex

point character size. See help on par.

digits

number of digits used to print axis values and other numbers.

num.ticks

number of tick marks draw.

tol

proportion of white space at the margins of plot

uin

desired values for the units per inch parameter. If of length 1, the desired units per inch on the x axis.

xlim, ylim

the ranges to be encompassed by the x and y axes. Useful for centering the plot.

right

logical; if TRUE, the pedals are right-closed (left open) intervals.

shrink

maximum length of the pedals, it can be used to plot several graphics with the same scale.

...

further parameters ignored for now.

Value

• x
  directions
• y
  magnitudes
• table
  Matrix output of the counts of wind direction and magnitude. Columns are in the same units as the data, according to step size, and rows are based on the increment size.
• number.obs
  Total number of observations.
• number.calm
  The number of calm observations omitted from the wind rose plot.
• breaks
  extremes of the pedals.
• mids
  midpoints of pedals.
• call
  the match.call result.

Details

Following the convention of the National Weather Service, winds with a direction of 0 are considered calm, while winds with a direction of 360 degrees (2*pi radians) are assumed to be from the north. Calm winds are excluded from the wind rose creation. This wind rose preserve areas of pedals, that is counts are proportional to the area of the pedals rather than to the length of the pedals. This is also for the slides created for the magnitudes.

Examples

# Random distribution of direction and magnitude in degrees

dir <- circular(runif(100, 0, 360), units="degrees")
mag <-  rgamma(100, 15)
sample <- data.frame(dir=dir, mag=mag)

par(mfrow=c(2,2))
res <- windrose(sample)
## we join two pedals and keep the same shrink (scale of the plot)
breaks <- seq(0, 2 * pi, by = pi/6)
breaks <- breaks[-2]
windrose(sample, breaks=breaks, main="The same but with two pedals joined", shrink=res$shrink)
## change the rotation
sample <- data.frame(dir=circular(dir, units="degrees", rotation="clock"), mag=mag)
windrose(sample, breaks=breaks, main="Change the rotation", shrink=res$shrink)
## use geographics template
sample <- data.frame(dir=circular(dir, units="degrees", template="geographics"), mag=mag)
windrose(sample, breaks=breaks, main="Use the template 'geographics'", shrink=res$shrink)

x11()
## do the same plot but in radians
dir <- conversion.circular(dir)
windrose(x=dir, y=mag, xlim=c(-1.3, 1.3))
x11()
## magnify some part of the plot
windrose(x=dir, y=mag, xlim=c(0, 1.3))