selectpts: Internal Function: Select Probability Sample from a Set of...
In mhweber/spsurvey: Spatial Survey Design and Analysis

Selects a sample of size one or larger from a set of cells based on inclusion probabilities.

1	selectpts(rdx, xc, yc, dx, dy, pts)

`rdx`	Vector of the index value for selected cells.
`xc`	Vector of x-coordinates that define the cells.
`yc`	Vector of y-coordinates that define the cells.
`dx`	Width of the cells along the x-axis.
`dy`	Width of the cells along the y-axis.
`pts`	Data frame containing id values, x-coordinates, y-coordinates, and mdm values.