Dixon's 2-type contingency table tests
dixon(X, prepR = 0)bivariate ppp
for large patterns, makes it a bit easier to find nearest neighbours.
Computes the tests of segregation using nearest neighbour contingency tables introduced by Philip Dixon in his paper "Testing spatial segregation using a nearest-neighbor contingency table", Ecology, 75, p.1940-1948 (1994). The tests are an improvement on the Pielou's test of segregation. The test is defined only for two-type spatial pattern.
Philip Dixon: "Testing spatial segregation using a nearest-neighbor contingency table", Ecology, 75, p.1940-1948 (1994).