# How can i create a loop to generate daily averages from a csv. file for over four years and whose data was input at a 15minutes interval?

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CKJ on 1 Sep 2022
Commented: CKJ on 2 Sep 2022
the data looks like this

Cris LaPierre on 1 Sep 2022
Edited: Cris LaPierre on 1 Sep 2022
Use groupsummary and group the data by 'monthofyear' and 'dayofmonth' and the method set to mean. See this answer:
Here is a simple example
Date = [datetime(2016,6,4)+calyears(0:5)';datetime(2016,6,5)+calyears(0:5)'];
X = rand(size(Date));
Y = rand(size(Date));
Z = rand(size(Date));
tbl = table(Date,X,Y,Z)
tbl = 12×4 table
Date X Y Z ___________ _______ ________ _______ 04-Jun-2016 0.56436 0.95061 0.63577 04-Jun-2017 0.70903 0.050817 0.74741 04-Jun-2018 0.57119 0.54743 0.12786 04-Jun-2019 0.2342 0.21309 0.78041 04-Jun-2020 0.91886 0.353 0.45837 04-Jun-2021 0.3717 0.70704 0.72707 05-Jun-2016 0.58379 0.70093 0.39723 05-Jun-2017 0.41526 0.26787 0.13649 05-Jun-2018 0.15754 0.93554 0.50168 05-Jun-2019 0.69327 0.69517 0.38602 05-Jun-2020 0.93947 0.75884 0.64675 05-Jun-2021 0.26944 0.37348 0.22696
out = groupsummary(tbl,["Date","Date"],["monthofyear","dayofmonth"],'mean')
out = 2×6 table
monthofyear_Date dayofmonth_Date GroupCount mean_X mean_Y mean_Z ________________ _______________ __________ _______ _______ _______ 6 4 6 0.56156 0.47033 0.57948 6 5 6 0.5098 0.62197 0.38252
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CKJ on 2 Sep 2022
I was able to corrrect the error by critically analysing the help you had rendered in the first reply. THANKS very # I did not know group summary does the task very well.