grDevices (version 3.3)

xy.coords: Extracting Plotting Structures

Description

xy.coords is used by many functions to obtain x and y coordinates for plotting. The use of this common mechanism across all relevant Rfunctions produces a measure of consistency.

Usage

xy.coords(x, y = NULL, xlab = NULL, ylab = NULL, log = NULL,
          recycle = FALSE)

Arguments

x, y
the x and y coordinates of a set of points. Alternatively, a single argument x can be provided.
xlab, ylab
names for the x and y variables to be extracted.
log
character, "x", "y" or both, as for plot. Sets negative values to NA and gives a warning.
recycle
logical; if TRUE, recycle (rep) the shorter of x or y if their lengths differ.

Value

  • A list with the components
  • xnumeric (i.e., "double") vector of abscissa values.
  • ynumeric vector of the same length as x.
  • xlabcharacter(1) or NULL, the label of x.
  • ylabcharacter(1) or NULL, the label of y.

Details

An attempt is made to interpret the arguments x and y in a way suitable for bivariate plotting (or other bivariate procedures).

If y is NULL and x is a [object Object],[object Object],[object Object],[object Object] In any other case, the x argument is coerced to a vector and returned as y component where the resulting x is just the index vector 1:n. In this case, the resulting xlab component is set to "Index".

If x (after transformation as above) inherits from class "POSIXt" it is coerced to class "POSIXct".

See Also

plot.default, lines, points and lowess are examples of functions which use this mechanism.

Examples

Run this code
xy.coords(stats::fft(c(1:9)), NULL)

with(cars, xy.coords(dist ~ speed, NULL)$xlab ) # = "speed"

xy.coords(1:3, 1:2, recycle = TRUE)
xy.coords(-2:10, NULL, log = "y")
##> warning: 3 y values <= 0 omitted ..

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