function drawpairscan(Fpr, Fnt, chrid, chroms, header)
%draw a pairscan figure
%figure
Z = Fpr + Fnt';
m = size(Z,1);
surf([[Z,zeros(m,1)];zeros(1,m+1)])
%shading flat
colormap(jet)
axis([1,m+1,1,m+1])
%caxis([0,6.25])
view(2)
axis square
h1 = colorbar
for i = chroms
   x = find(chrid == i);
   polyx = [min(x); min(x); max(x)+1; max(x)+1];
   polyy = [min(x); max(x)+1; max(x)+1; min(x)];
   patch(polyx,polyy,30*ones(4,1), 'w')
end
mp = zeros(1,max(chrid));
dx = 1;
for i = chroms
   mp(dx) = mean(find(chrid==i));
   dx = dx + 1;
end
set(gca,'Ticklength',[0 0])
set(gca,'XTickLabel',[])
set(gca,'YTickLabel',[])
label = [num2str(chroms')];

for i = 1:length(chroms)
   h = text(mp(i)+0.5, mp(i)+0.5, 32, label(i,:));
   set(h,'FontSize',6,'VerticalAlignment','Middle','HorizontalAlignment','Center')
end
title(header)