Sorting maximum value array by same date and time
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I have an array of very large size 708273*3,the first and second column representing time and date respectively. Each time and date have many values. I need to find out maximum value from that. I have no idea with how to short those value from excel. Sample data file name "test1".
Any help will be highly appreciated.
With best regards,
Somnath
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回答(1 个)
Ameer Hamza
2020-5-28
Try this
T = readtable('test1.xlsx');
grps = findgroups(T.Time, T.Date);
max_vals = splitapply(@max, T.Value, grps);
T.MaximumValue = max_vals(grps);
writetable(T(:,'MaximumValue'), 'test1.xlsx', 'Range', 'D1')
24 个评论
SOMNATH MAHATO
2020-5-28
Dear Ameer,
Thank you for your responce.
But this program is not working.
If possible can you send a screen short of your program. If you want more sample data, i can share with you.
regards,
Somnath
SOMNATH MAHATO
2020-5-28
if possible can you send the details code in my email somnathmahato1@gmail.com. i am a new user in matlab.
Ameer Hamza
2020-5-28
In MATLAB, the file name must not contain spaces. Remove the spaces from the name of the script and the use green button in the toolbar to run the code.
Ameer Hamza
2020-5-28
You haven't changed the name of your script. Change it from "maximum elevaltion angle short.m" to something else, and it should not have spaces in its name.
SOMNATH MAHATO
2020-5-28
this error shows:
Warning: Variable names were modified to make them valid MATLAB identifiers.
Undefined function or variable 'findgroups'.
Error in test (line 2)
grps = findgroups(T.Time,T.Date);
Ameer Hamza
2020-5-28
Try this
T = readtable('test2.xlsx');
temp = num2str(T.Time, 16);
temp = mat2cell(temp, ones(size(temp,1),1), size(temp,2));
[~, ~, grps] = unique(strcat(temp, T.Date));
max_vals = splitapply(@max, T.Value, grps);
T.MaximumValue = max_vals(grps);
writetable(T(:,'MaximumValue'), 'test2.xlsx', 'Range', 'D1')
Ameer Hamza
2020-5-28
Try this
T = readtable('test2.xlsx');
temp = num2str(T.Time, 16);
temp = mat2cell(temp, ones(size(temp,1),1), size(temp,2));
[~, ~, grps] = unique(strcat(temp, T.Date));
u_grps = unique(grps);
max_vals = zeros(numel(u_grps), 1);
for i=1:numel(u_grps)
max_vals(i) = max(T.Value(grps==u_grps(i)));
end
T.MaximumValue = max_vals(grps);
writetable(T(:,'MaximumValue'), 'test2.xlsx', 'Range', 'D1')
SOMNATH MAHATO
2020-5-28
This error shows
• The workbook you are trying to save has the same name as a currently open workbook.
Help File: xlmain11.chm
Help Context ID: 0
Error in test (line 11)
writetable(T(:,'MaximumValue'),'test.xlsx','Range','D1')
SOMNATH MAHATO
2020-5-28
When, i have select the hole data file... its can't short properly. Can please you check it.
Ameer Hamza
2020-5-28
Try this. You may need to verify if the output is correct
T = readtable('test4.xlsx');
T = table2cell(T(:,1:3));
temp = num2str([T{:,1}].', 16);
temp = mat2cell(temp, ones(size(temp,1),1), size(temp,2));
[~, ~, grps] = unique(strcat(temp, T(:,2)));
u_grps = unique(grps);
max_vals = zeros(numel(u_grps), 1);
for i=1:numel(u_grps)
max_vals(i) = max([T{grps==u_grps(i), 3}]);
end
T = table(max_vals(grps), 'VariableNames', {'MaximumValue'});
writetable(T(:,'MaximumValue'), 'test4.xlsx', 'Range', 'D1')
SOMNATH MAHATO
2020-5-28
Data start time and date 12:28:09 PM and 22-05-2020
Data end time and date 12:30:02 and 23-05-2020
according time and date ,data haven't shortlisted. I need to short the data like-
Time Date Maximum value
12:28:09 22-05-2020
12:30:02 23-05-2020
i can't short my data in the above format
Ameer Hamza
2020-5-28
Yes, it seems possible, but the first column of the excel file is in some custom format, which is not recognized by MATLAB. You may first need to change the data type of the first column in Excel and then follow the code in my comment to only save each maximum value once.
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