how to select range of dates

I have stock data of 10 years with two columns.One is the stocks which is numeric and the other is dates which are in datetime format.I converted datetime to Numeric also. I want to calculate mean for each year using mean(stock) formula. But I dont know how can I select the data for each year separately? The days are also not continuous as there are holiday gaps How can I get the range of data for one year e.g like from jan 1 ,2007 to dec 31 2007 and then get its mean

Answer 1

[per isakson]

Hint:

accumarray( t.Year-2007+1, stock, [], @mean )

where t is a datetime object

[rohail khan]

thank you so much.You are amazing

[Peter Perkins]

There are any number of ways to do this. accumarray is old school. full(sparse(...)) would have been even older school. More beginner-friendly ways include findgroups/splitapply, and varfun with a grouping variable. And in R2018a, groupsummary.