Find the closest spot to a target point

Returns the row of `df` corresponding to the spot nearest to the target coordinates `(tx, ty)` using squared Euclidean distance.

Usage

closest_spot(df, tx, ty)

Arguments

df

A data frame containing at least numeric columns `x` and `y` representing spot coordinates.

tx

Numeric scalar; target x-coordinate.

ty

Numeric scalar; target y-coordinate.

Value

A one-row data frame (same columns as `df`) corresponding to the closest spot. The result is always a data frame (`drop = FALSE`).

Details

The function minimizes `(x - tx)^2 + (y - ty)^2`. Squared distances are used for efficiency; taking the square root is unnecessary for argmin.

If multiple spots are tied for the minimum distance, the first occurrence is returned (as per `which.min()`).

Examples

df <- data.frame(x = c(0, 2, 5), y = c(0, 2, 1), id = c("a", "b", "c"))
closest_spot(df, tx = 1.9, ty = 2.1)
#>   x y id
#> 2 2 2  b