Plots with Geometrically Equal Scales

Version of a scatterplot with scales chosen to be equal on both axes, that is 1cm represents the same units on each

eqscplot(x, y, ratio = 1, tol = 0.04, uin, ...)

Arguments

x	vector of x values, or a 2-column matrix, or a list with components `x` and `y`
y	vector of y values
ratio	desired ratio of units on the axes. Units on the y axis are drawn at `ratio` times the size of units on the x axis. Ignored if `uin` is specified and of length 2.
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.
...	further arguments for `plot` and graphical parameters. Note that `par(xaxs="i", yaxs="i")` is enforced, and `xlim` and `ylim` will be adjusted accordingly.

Value

invisibly, the values of uin used for the plot.

Side Effects

performs the plot.

Details

Limits for the x and y axes are chosen so that they include the data. One of the sets of limits is then stretched from the midpoint to make the units in the ratio given by ratio. Finally both are stretched by 1 + tol to move points away from the axes, and the points plotted.

Note

Arguments ratio and uin were suggested by Bill Dunlap.

References

Venables, W. N. and Ripley, B. D. (2002) Modern Applied Statistics with S. Fourth edition. Springer.