pub fn extract_contours(
grid: &[f64],
nx: usize,
ny: usize,
x_min: f64,
y_min: f64,
dx: f64,
dy: f64,
levels: &[f64],
) -> (Vec<Value>, Vec<Value>, Vec<Value>, Vec<Value>)Expand description
Extract contour line segments from a regular grid at specified level thresholds. Returns vectors of (x, y, level, group_id) for each segment endpoint.