fix #545, calcMeanFroh() does the wrong thing in multichrom models

Author: bhaller

VERSIONS

@@ -18,6 +18,7 @@ development head (in the master branch):
 	calcFST() with a windowed range (start/end) would error; was missing a unit test (#548)
 	calcSFS() with an integer (non-NULL) binCount would error in multi-chromosome models if mutations from multiple chromosomes (or NULL) were given
 	survival() callback that moves individuals did not correctly update has_null_haplosomes_, leading to a crash or a DEBUG raise (#549)
+	calcMeanFroh() did not focus on the specified chromosome correctly, in multi-species models, and thus produced incorrect results (#545)
 
 
 version 5.0 (Eidos version 4.0):

core/slim_functions.cpp

@@ -261,13 +261,14 @@ R"V0G0N({
 		
 		for (chr in chromosomes)
 		{
-			// get the haplosomes we will operate over
+			// get the haplosomes we will operate over, for the focal chromosome
 			haplosomes = individual.haplosomesForChromosomes(chr, includeNulls=F);
 			
 			if (haplosomes.length() != 2)
 				next;
 			
-			het_pos = individual.mutationsFromHaplosomes("heterozygous").position;
+			// get the mutations that are heterozygous, for the focal chromosome
+			het_pos = individual.mutationsFromHaplosomes("heterozygous", chromosomes=chr).position;
 			het_pos_1 = c(-1, het_pos);
 			het_pos_2 = c(het_pos, chr.lastPosition + 1);
 			roh = (het_pos_2 - het_pos_1) - 1;