Swap x and y in a formula — swap

By default a formula of x on y is converted into a formula of y on x, while the reverse swap is done only if backward = TRUE.

Usage

swap_xy(f, backwards = FALSE)

Arguments

f: formula An R model formula
backwards: logical If NULL the swap is done irrespective of the variable in the lhs.

Value

A copy of f with x and y swapped by each other in the lhs and rhs.

Details

If backwards = TRUE, a formula with x in the lhs is always, returned. If backwards = FALSE, a formula with y in the lhs is always, returned. If backwards = NULL x and y are always swapped.

This function is meant to be used only as a helper within 'ggplot2' statistics. Normally together with geometries supporting orientation when we want to automate the change in orientation based on a user-supplied formula. Only x and y are exchanged, and in other respects the formula is rebuilt copying the environment from f.