How to find the corresponding date to each found maximum value?

I have a timetable 79880x42 with precipitation data:

Date                               Station 1  Station 2  Station 3 ...
'01-Jan-2011 00:00:00'	0	          0	           0
'01-Jan-2011 01:00:00'	0.3	          0	           0
'01-Jan-2011 02:00:00'	0.4	          0	           0.6
'01-Jan-2011 03:00:00'	1.2	          0	           0.8

I found the maximum value TTmax = retime(tt,'yearly','max'), tt=timetable, but this only gives the matrix with max values

How do I get the yearly maximum values of each station WITH the corresponding date and time?

[Lei Hou]

Hi SaaraL,

I need more information about how you want to get. I tried the following.

>> tt = timetable((1:79880)',0.1*(1:79880)',0.01*(1:79880)','StartTime',datetime(2011,1,1,0,0,0),'TimeStep',hours(1),'VariableNames',{'Station 1' 'Station 2' 'Station 3'});
>> TTmax = retime(tt,'yearly','max')

TTmax =

  10×3 timetable

       Time        Station 1    Station 2    Station 3
    ___________    _________    _________    _________

    01-Jan-2011       8760          876         87.6  
    01-Jan-2012      17544       1754.4       175.44  
    01-Jan-2013      26304       2630.4       263.04  
    01-Jan-2014      35064       3506.4       350.64  
    01-Jan-2015      43824       4382.4       438.24  
    01-Jan-2016      52608       5260.8       526.08  
    01-Jan-2017      61368       6136.8       613.68  
    01-Jan-2018      70128       7012.8       701.28  
    01-Jan-2019      78888       7888.8       788.88  
    01-Jan-2020      79880         7988        798.8  
    
    

Regarding the above result, for example 8760, it is the maximum value of "Station 1" for year 2011. It seems what you want. If not, please tell me more about your input timetable and what you want to get.

[SaaraL]

The maximum values for each station are at different times, so I need to get the maximum for each station for each year and at what time was the maximum registered. Is that possible? It should look like:

Registered time Station 1 max (mm) Registered time Station 2 max (mm)

2011 07.07.2011 13:00 46 18.06.2011 11:00 36

And so forth

Answer 1

[Dongyue]

Hi SaaraL,

Please try the following code, and hope this will help:

clear; clc;
tt = timetable((1:79880)',0.1*(1:79880)',0.01*(1:79880)','StartTime',datetime(2011,1,1,0,0,0),'TimeStep',hours(1),'VariableNames',{'Station 1' 'Station 2' 'Station 3'});
TTmax = retime(tt,'yearly','max');
nrow = size(TTmax,1);
ncol = size(TTmax,2);

for row = 1:nrow
    tmp = TTmax(row,:);
    yr = year(tmp.Time);
    fprintf('Year:%d | ',yr)
    for col = 1:ncol
        station = TTmax.Properties.VariableNames{col};
        mx = tmp.(station);
        tmx = tt.Time(tt.(station)==mx & year(tt.Time)==yr);
        fprintf("%s: %s | %d  ||  ",station,tmx, mx)
    end
    fprintf('\n')
end

Year:2011 | 

Station 1 : 31-Dec-2011 23:00:00 | 8760  ||  Station 2 : 31-Dec-2011 23:00:00 | 876  ||  Station 3 : 31-Dec-2011 23:00:00 | 8.760000e+01  ||  

Year:2012 | 

Station 1 : 31-Dec-2012 23:00:00 | 17544  ||  Station 2 : 31-Dec-2012 23:00:00 | 1.754400e+03  ||  Station 3 : 31-Dec-2012 23:00:00 | 1.754400e+02  ||  

Year:2013 | 

Station 1 : 31-Dec-2013 23:00:00 | 26304  ||  Station 2 : 31-Dec-2013 23:00:00 | 2.630400e+03  ||  Station 3 : 31-Dec-2013 23:00:00 | 2.630400e+02  ||  

Year:2014 | 

Station 1 : 31-Dec-2014 23:00:00 | 35064  ||  Station 2 : 31-Dec-2014 23:00:00 | 3.506400e+03  ||  Station 3 : 31-Dec-2014 23:00:00 | 3.506400e+02  ||  

Year:2015 | 

Station 1 : 31-Dec-2015 23:00:00 | 43824  ||  Station 2 : 31-Dec-2015 23:00:00 | 4.382400e+03  ||  Station 3 : 31-Dec-2015 23:00:00 | 4.382400e+02  ||  

Year:2016 | 

Station 1 : 31-Dec-2016 23:00:00 | 52608  ||  Station 2 : 31-Dec-2016 23:00:00 | 5.260800e+03  ||  Station 3 : 31-Dec-2016 23:00:00 | 5.260800e+02  ||  

Year:2017 | 

Station 1 : 31-Dec-2017 23:00:00 | 61368  ||  Station 2 : 31-Dec-2017 23:00:00 | 6.136800e+03  ||  Station 3 : 31-Dec-2017 23:00:00 | 6.136800e+02  ||  

Year:2018 | 

Station 1 : 31-Dec-2018 23:00:00 | 70128  ||  Station 2 : 31-Dec-2018 23:00:00 | 7.012800e+03  ||  Station 3 : 31-Dec-2018 23:00:00 | 7.012800e+02  ||  

Year:2019 | 

Station 1 : 31-Dec-2019 23:00:00 | 78888  ||  Station 2 : 31-Dec-2019 23:00:00 | 7.888800e+03  ||  Station 3 : 31-Dec-2019 23:00:00 | 7.888800e+02  ||  

Year:2020 | 

Station 1 : 11-Feb-2020 07:00:00 | 79880  ||  Station 2 : 11-Feb-2020 07:00:00 | 7988  ||  Station 3 : 11-Feb-2020 07:00:00 | 7.988000e+02  ||  

Best,

Dongyue