jtacc

Accuracy of a journey-to-crime surface on a solved series

R

jtacc(prob, win, base)

Given a surface over the grid of jtsurf() and the offender’s known base: the surface’s value in the base’s cell, the hit score (the share of the grid searched, in decreasing order of the surface, up to and including the base’s cell), in the best and the worst order of ties (Rossmo 2000; Canter et al. 2000), and the error distance from the peak cell’s centre to the base.

Parameters

prob

The surface: a matrix of values from 0, nx rows by ny columns, as jtsurf() returns.

win

The grid’s rectangle, as given to jtsurf().

base

The known base, c(x, y), inside win.

Returns

A named numeric vector: p (the value in the base’s cell), hitbest and hitworst (shares from 0 to 1), err (the error distance), peak and cell (the peak’s and the base’s cell, numbered down the columns).

References

Rossmo, D. K. (2000). Geographic Profiling. CRC Press.

Examples

s <- jtsurf(c(2, 3, 4), c(2, 4, 3), win = c(0, 6, 0, 6), nx = 30,
            ny = 30, type = "negexp", par = c(1, 1), mode = "lik")
jtacc(s$prob, win = c(0, 6, 0, 6), base = c(3.2, 2.9))

Generated from the R help page: jtacc in the R reference.