Accumulate rain events with determined dry period

Question

Danilo M 2018-11-20

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https://ww2.mathworks.cn/matlabcentral/answers/431038-accumulate-rain-events-with-determined-dry-period

评论： Danilo M 2018-11-21

I have a rain time series with 15 minutes between data:

yyyy mm dd hh mm ss rain

2010 1 1 0 0 0 0.2

2010 1 1 0 15 0 0.4

2010 1 1 0 30 0 0

[...]

And I need to accumulate every rain value restarting the sum every time the station had at least 24 hours without rain, getting a matrix with start and end dates of each rain event and the accumulated rain during the period:

start_rain end_rain accumulated_rain

2010-1-1-0:0:0 2010-1-4-0:0:0 12

2010-1-7-0:0:0 2010-1-13-0:0:0 23

The date format above is only for exampe, could be in datenum

Any suggestions about how can I do this on MatLab?

Tks

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Andrei Bobrov 2018-11-20

Please attach small example your data as mat-file.

Danilo M 2018-11-21

ex_rain.mat

Here is an small example of rain data. The rain data is on 7th row.

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Answer 1

Andrei Bobrov 2018-11-21

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https://ww2.mathworks.cn/matlabcentral/answers/431038-accumulate-rain-events-with-determined-dry-period#answer_348126

编辑：Andrei Bobrov 2018-11-21

load('ex_rain.mat')
TT = timetable('RowTimes',datetime(example(:,1:6)),example(:,7),'v',{'rain'});
TT1 = retime(TT,'daily','sum');
p = TT1.rain~=0;
p1 = [0;p;0];
Time_interv = TT1.Time([strfind(p1(:)',[0 1]);strfind(p1(:)',[1 0])-1]');
ii = cumsum(diff(p1)==1);
ii = ii(1:end-1).*p + 1;
rain_int = accumarray(ii,TT1.rain);
rain_int = rain_int(2:end);
Rain_out = table(Time_interv,rain_int);

same variant but without timetable

[Date0,~,i0] = unique(example(:,1:3),'rows');
rain_daily = table(datetime(Date0),accumarray(i0,example(:,7)),'v',{'Date','rain'});
p = rain_daily.rain~=0;
p1 = [0;p;0];
Time_interv = rain_daily.Date([strfind(p1(:)',[0 1]);strfind(p1(:)',[1 0])-1]');
ii = cumsum(diff(p1)==1);
ii = ii(1:end-1).*p + 1;
rain_interv = accumarray(ii,rain_daily.rain);
rain_interv = rain_interv(2:end);
Rain_out = table(Time_interv,rain_interv);

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Danilo M 2018-11-21

Thanks Andrei! I could run the code without timetable and did exactly what I need.

I just have two doubts about the code. There's a way to put the hour on Time_interval table? Because I need to calculate rain intensity (mm/hour), so I need to know the exactly interval.

And if I want to change the dry period interval, like 36 or 48 hours without rain, what line I can make it?

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