finding the name which are the same in an Excell file and make structure and sub-structure form them

Hi everyone! I'm lerning Matlab and work with structur types . I appreciated if you help me with my problem. i read about unique but need help. Here is my question i have a (n x 3) matrix or better say an Excel file with 3 column and many rows it look like this:

Name time value

AA t1 v1

BB t2 v2

CC t3 v3

AA t4 v4

DD t5 v5

AA t6 v6

BB t7 v7

And so on. Now I must find all the name that are the same ,make Structure from them and as sub-structure it should contain the times and the values of that specified name ,so that it should be like this:

Let say this excel file calles excel_file and the main structure called str , so str.name will be names in first row :

str.names= excel_file( : , 1 )

Now I don’t know how to gather the values and times as sub-structure for each names . as example

str.AA should contain a substructure which this sub-struct contains all the infos about AA which are t1,v1 , t4,v4 and t6,v6

And so on for str.BB : t2,v2 -t7,v7 and str.CC t3,v3 and str.DD t5,v5

the Names are acually signals which are happend in different times and every signal has different value . it's mean in the Excel file will be many equal signal_names which are happend in different times and have different value .And the data should just be sorted in structure and sub structurs and the goal is that ,when i call a specified signal_name as a structure ,I shoud be able to see a sub structure containg all the Times and value for this signal_name

in an other way str.name is actually a (n,1) big matrix . and n is number of different names. so if the exell has 100 rows( as 100 names ) there are as example n=70 different names in it.

also str.name has two substructures str.name.time and str.name.value , both of these two are (m,1) big, but m is different for each str.name becaues names are repeated differently

Or in an other way i want to know that in which times ist the name AA happened and what are the value and so on for other names

Thank you for your help in advance

[Stephen23]

A table would be much better suited to your data:

https://www.mathworks.com/help/matlab/tables.html

You can probably import the data using readtable:

https://www.mathworks.com/help/matlab/ref/readtable.html

[Walter Roberson]

Are the time entries character vectors, or are they numeric?

[Milad Ghobadi]

Hi, the times are in timestamp format also numeric something like 1567683075.082312 values are also numeric

[Milad Ghobadi]

Hi Stephen thank you . I have read your answers from other questions . I think unique will not be helpfull in my problem am i right?

[Guillaume]

Like Stephen, I think you would be better served by a single table (or timetable since you appear to have time). You probably don't even need to split the table. You can easily perform aggregate function on a single table/timetable, e.g calculate the mean of value for each unique Name with functions such as groupsummarry.

If you explain a bit more what you want out of your data, we can give more details.

edit: following your addition to the question:

It would be better if you explained what you want to do not in term of code but in term of overall objective and what the data represent. I.e forget about structures, tables, etc. Which to use depends on what result you ultimately want and most likely structures are not the easiest solution.

It would appear that you have many signals sampled at various time. What do you want to do with that?

[Milad Ghobadi]

Hi thank you for your comment . exactly there is many signal at various time with various value as you said and the Object is to sort these signals with same name and gather all the value and time which has equal signal name so that when i search for a specified signal name i could be able to see all the values and times of that signal.

[Walter Roberson]

Numeric values such as those can be converted to datetime using

datetime(Number, 'convertfrom', 'posix')

[Milad Ghobadi]

Thank you . But the goal is to gather all the values and times with same signal namen in a sub structure

[Guillaume]

"But the goal is to gather all the values and times with same signal namen in a sub structure"

No, that's a not a goal. You're again making the mistake of describing an implementation of a goal, not the goal itself. As we've said many times now, using structures is most likely the wrong approach.

Answer 1

[Guillaume]

From your description, it really sounds like you would be better off using a table rather than splitting the data into structures. Tables are much easier to work with. Something like this should get you started:

sourcefile = 'C:\somewhere\somefolder\somefile.xlsx';

signaldata = readtable(yoursourcefile);  %probably works out of the box if your excel file is well structured. Can be customised if needed to cope with more complicated files
%the following assumes that the excel file has a header row containing 'Name', 'Time', 'Signal'
signaldata = sortrows(signaldata, 'Name', 'Time');  %optional: reorder the rows, first by name, then by time, for easier visualisation

With that it's straightforward to filter on a particular signal

signaldata(strcmp(signaldata.Name, 'AA', :)  %get section of table corresponding to signal AA

or plot the evolution of each signal against time:

figure; hold('on');
rowfun(@plot, signaldata, 'GroupingVariables', 'Name'); %plot Value VS Time for each signal

or for an even better plot:

figure; hold('on');
rowfun(@(n, t, v) plot(t, v, 'DisplayName', n{1}), signaldata, 'GroupingVariables', 'Name', 'InputVariables', 1:3); %plot Value VS Time for each signal
legend('show')

[Milad Ghobadi]

thank you Guillaume, I learned a lot from your answer .