Converting 15 minute data to daily data

I have 2976x42 matrix were data was collected continuously every 15 minutes for a month. The first column containts the year, date and time. Now I want to get an averages per day, in other words convert the 15 minute data to daily data. Each day has 96 data sets. What is the best code i can use?

Answer 1

[KSSV]

Read about retime

[Willard Zvarevashe]

Thanks for this it worked.