v=randi(9,1,55) % Example
n=ceil(numel(v)/10)*10
v(end+1:n)=nan
a=reshape(v,10,[])
idx=~isnan(a)
for k=1:size(a,2)
out(k)=sum(a(idx(:,k),k))/sum(idx(:,k))
end
Or
v=randi(9,1,55) % Example
n=ceil(numel(v)/10)*10
v(end+1:n)=nan
a=reshape(v,10,[])
out=nanmean(a)
