Find max values for each year

Question

Danilo M 2018-12-21

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/436800-find-max-values-for-each-year

评论： Mahtab Moalemi 2020-4-17

采纳的回答： Star Strider

在 MATLAB Online 中打开

I have a time series matrix with hourly rain data like this:

[year month day hour minute secont rain]

rain = [2008 1 12 8 0 0
1 12 9 0 0
1 12 10 0 0
1 12 11 0 0
1 12 12 0 0.2
1 12 13 0 0.2
1 12 14 0 1
1 12 15 0 1.6
1 12 16 0 2.2
1 12 17 0 1.6
1 12 18 0 0.8
1 12 19 0 1.6
1 12 20 0 0.8
1 12 21 0 0.6
1 12 22 0 0.6
1 12 23 0 0.8
1 13 0 0 0.2
1 13 1 0 1];

And I need to find the max value of rain(:,7) for each year, resulting in a matrix like

max = [2008 43.2
41.4
30.4
36.6
38.0];

How can I do this on MatLab?

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Answer 1

Star Strider 2018-12-21

2
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https://ww2.mathworks.cn/matlabcentral/answers/436800-find-max-values-for-each-year#answer_353476

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Your ‘rain’ array does not exactly match the header information you posted for it, since there are only 6 columns.

This fills in the ‘seconds’ column with a vector of zeros, then does what you requested:

rain = [2008 1 12 8 0 0
        2008 1 12 9 0 0
        2008 1 12 10 0 0
        2008 1 12 11 0 0
        2008 1 12 12 0 0.2
        2008 1 12 13 0 0.2
        2008 1 12 14 0 1
        2008 1 12 15 0 1.6
        2008 1 12 16 0 2.2
        2008 1 12 17 0 1.6
        2008 1 12 18 0 0.8
        2008 1 12 19 0 1.6
        2008 1 12 20 0 0.8
        2008 1 12 21 0 0.6
        2008 1 12 22 0 0.6
        2008 1 12 23 0 0.8
        2008 1 13 0 0 0.2
        2008 1 13 1 0 1];
Times = datetime([rain(:,1:5) zeros(size(rain,1),1)]);              % Create ‘datetime’ Array
TData = timetable(Times, rain(:,6));                                % Convert To ‘timetable’
YrMean = retime(TData, 'yearly', 'max');                            % Yearly Maximum
Max = [YrMean.Times.Year YrMean.Var1]