Separate all data from table by date

Hi everyone!

I need to separate data in a table based on their dates. I cannot seem to figure out the code for this. I have found several options such as datenum and timetable. The datenum option gives me an error because the dates are not a string and datestr does not function either. The dates are displayed in the following format : DD/MM/YYYY. I have also tried converting the table to a structure but this just displays the date as: 1x1 datetime

[Ameer Hamza]

Can you show an example of your table content, or better yet if you could share a sample mat file, which could contain the table data.

[Debbie Oomen]

This is the table content. Thanks for the help

Answer 1

[Ameer Hamza]

One possible solution is to use splitapply(). It will split your table into several tables based on dates

splitapply(@(x) {x}, myTable{:,:}, findgroups(myTable{:, 1}))

this supposes that dates are present in the first column of the table myTable.

[Debbie Oomen]

This gives me an error:

Error using loaddata (line 25)
Unable to concatenate the specified table variables.

Error in thesis1>readfile_Callback (line 282)
loaddata

Error in gui_mainfcn (line 95)
        feval(varargin{:});

Error in thesis1 (line 42)
    gui_mainfcn(gui_State, varargin{:});

Error in
matlab.graphics.internal.figfile.FigFile/read>@(hObject,eventdata)thesis1('readfile_Callback',hObject,eventdata,guidata(hObject))

Caused by:
    Error using datetime/horzcat (line 1292)
    All inputs must be datetimes or date/time character vectors or date/time strings.

[Ameer Hamza]

for your table, following line will work

splitapply(@(x) {x}, table2cell(data), findgroups(data{:, 1}));

[Debbie Oomen]

Thanks Ameer! This works. Now, to do analysis on this data I assume I would need to use a loop?

[Debbie Oomen]

I need to analyse one cell of each date and save this per day. What would be the best/easiest way to do this?

[Ameer Hamza]

Does it depend on what you want to analyze? cellfun() might be an option since it can apply a function on every cell in a cell array and save the output in a variable.

Answer 2

[Peter Perkins]

Debbie, Ameer's solution answers your question, but you should ask yourself why you want to split your data up. There are lots of things you can do by applying functions to groups of data while they are still within a table. In fact, findgroups/splitapply is one of the ways to do that.

Very often, you are better off leaving the data all in one container.

[Debbie Oomen]

Thank you Peter, but how would I do this? I have a file with an amount of data for 10 days and want to get data from each individual day.

[Peter Perkins]

I don't know what you mean by "get". If your goal is to split up the data, then you should do that, and Ameer's sol'n works. But I am suggesting that your goal is probably more like "find the mean temperature for each day", and you don't need to split up your data to do that.