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Rotate points in a 2-d plane

Source: R/simutil-rotate_points.r
rotate_points.Rd

Rotate points around a point in a 2-d plane

Usage

rotate_points(x, y, theta, focus)

Arguments

x

A numeric vector of x coordinates; minimum of 2.

y

A numeric vector of y coordinates; minimum of 2.

theta

A numeric scalar with the angle of rotation in degrees; positive is clockwise.

focus

A numeric vector of x (first element) and y (second element) coordinates for the point around which x and y will rotate.

Value

A two-column data frame containing:

x

x coordinates

y

y coordinates

Details

Points are shifted to be centered at the focus, then rotated using a rotation matrix, then shifted back to original focus.

Note

This function is called from crw_in_polygon()

Author

C. Holbrook (cholbrook@glfc.org)

Examples

x <- runif(10, 0, 10)
y <- runif(10, 0, 10)
plot(x, y, type = "b", pch = 20)
foo <- rotate_points(x, y, 20, c(5, 5))
points(foo$x, foo$y, type = "b", pch = 20, col = "red")