# Hello, I have a table contains the calendar day of the year and 24-hour frequency. How to get daily max, min, and average temperature from the table?

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Sanley Guerrier on 11 Jul 2023
Commented: Sanley Guerrier on 11 Jul 2023
Star Strider on 11 Jul 2023
A relatively straightforward way is to use table2timetable and then retime. The year-month-day information is a bit ambiguous (at least in the sample provided), so you may need to specify it in an options structure created by the detectImportOptions function.

Voss on 11 Jul 2023
Here's one approach:
% a table similar to yours, with only a few days, and only the relevant columns:
t = table(repelem({'2005-01-01'; '2005-02-01'; '2005-03-01'},96,1),-12.35+0.1*(1:288).','VariableNames',{'DAY','AIR_TEMP_DEG_C'})
t = 288×2 table
DAY AIR_TEMP_DEG_C ______________ ______________ {'2005-01-01'} -12.25 {'2005-01-01'} -12.15 {'2005-01-01'} -12.05 {'2005-01-01'} -11.95 {'2005-01-01'} -11.85 {'2005-01-01'} -11.75 {'2005-01-01'} -11.65 {'2005-01-01'} -11.55 {'2005-01-01'} -11.45 {'2005-01-01'} -11.35 {'2005-01-01'} -11.25 {'2005-01-01'} -11.15 {'2005-01-01'} -11.05 {'2005-01-01'} -10.95 {'2005-01-01'} -10.85 {'2005-01-01'} -10.75
% group the DAYs together:
[g, g_id] = findgroups(t.DAY);
% (g_id contains your days, if you should need it:)
g_id
g_id = 3×1 cell array
{'2005-01-01'} {'2005-02-01'} {'2005-03-01'}
% find the min, max, and mean of AIR_TEMP_DEG_C for each DAY:
[min_all, max_all, mean_all] = splitapply(@get_min_max_mean, t.AIR_TEMP_DEG_C, g)
min_all = 3×1
-12.2500 -2.6500 6.9500
max_all = 3×1
-2.7500 6.8500 16.4500
mean_all = 3×1
-7.5000 2.1000 11.7000
function [min_val, max_val, mean_val] = get_min_max_mean(in)
min_val = min(in);
max_val = max(in);
mean_val = mean(in);
end
Sanley Guerrier on 11 Jul 2023
I appriciate it. That helps a lot!

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