activityByHour(s,contestName)

function activityByHour(s,contestName)
d = [s.date];
bins = floor(d(1)):(1/24):ceil(d(end));
count = histc(d,bins);
nonempty = find(count ~= 0);
range = min(nonempty):max(nonempty);
%stem(bins(range),count(range),'Marker','none','Color','k')
bar(bins(range)+(bins(2)-bins(1))/2,count(range),'FaceColor','b','EdgeColor','b')
box on
datetick
hold on
set(gca,'GridLineStyle','-')
xlabel('hour of submission')
ylabel('number of entries')
title(['Histogram of All ' num2str(length(s)) ' Contest Entries'])

[periods,periodLabels,prizeTimes,prizeLabels] = getMilestones(contestName);

% Shade background of different time periods.
ylim = get(gca,'ylim');
cmap = brighten(cool(size(periods,1)),.8);
ymax = ylim(2)-5;
for i = 1:size(periods,1)
    area([periods(i,1) periods(i,2) periods(i,2) periods(i,1)],[ylim(1) ylim(1) ylim(2) ylim(2)], ...
        'FaceColor',cmap(i,:),'EdgeColor',lightGray);
    text(mean([periods(i,1) periods(i,2)]),ymax-5,periodLabels{i},'HorizontalAlignment','center');
    kids = get(gca,'Children');
    set(gca,'Children',[kids(3:end); kids(1:2)]);
end

% Label contest deadlines.
for i = 1:length(prizeTimes)
    plot([prizeTimes(i) prizeTimes(i)],get(gca,'Ylim'),'color','k')
    [unused,ind]=min(abs(prizeTimes(i)-bins));
    ypos = count(ind-1)+10;
    %ypos = ymax-10;
    text(prizeTimes(i),ypos,prizeLabels{i},'HorizontalAlignment','center');
end
axis tight