Shift a point along a given direction vector

Translates a point `P` by an amount `offset` in the direction `(nx, ny)`. The returned point is: $$P' = (P_x + offset \cdot nx,\; P_y + offset \cdot ny).$$

Usage

shift_point(P, nx, ny, offset)

Arguments

P

A data frame with columns `x` and `y` representing the point to shift. If it contains multiple rows, only the first row is used.

nx

Numeric scalar; x-component of the direction vector.

ny

Numeric scalar; y-component of the direction vector.

offset

Numeric scalar; translation magnitude (in the same units as `x`/`y`). Positive values move in the `(nx, ny)` direction; negative values move in the opposite direction.

Value

A one-row data frame with columns `x` and `y` giving the shifted point.

Examples

# Shift the point (1, 2) by 3 units in the direction (0, 1)
P <- data.frame(x = 1, y = 2)
shift_point(P, nx = 0, ny = 1, offset = 3)
#>   x y
#> 1 1 5