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How to read from Excel columns into Signal analyzer app?

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farzad
farzad on 30 Apr 2020
Commented: Peter Perkins on 5 May 2020
Hi all
I read a two column signal ,time and displacement from Excel file and tried the Signal analyzer help page to convert it to something readable for the app. but
I was unsuccessfull in converting the Table time column into seconds.
str.st = mysig(:,1);
str.s1 = mysig(:,2);
T = struct2table(str);
T.st = seconds(T.st);
TT = table2timetable(T,'RowTimes','st');
Input data must be a real, numeric array.
I should mention that the structure contains two tables, and when I create T, I have a Table of tables and this might have caused the error.
it could have been much better that the signal analyzer app was able to internalize the data type conversion and adapt any parameter that was to be read.

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farzad
farzad on 30 Apr 2020
thank you , should I name all the columns ?
Error :
Row times must be specified as variable name or index, or as datetime or duration vector.
farzad
farzad on 30 Apr 2020
and by the way, the error is in the previous line, you corrected the next line
T.st = seconds(T.st);

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Accepted Answer

Peter Perkins
Peter Perkins on 30 Apr 2020
You must be leaving something out. If T.st is numeric, then T.st = seconds(T.st) creates a duration, and
TT = table2timetable(T,'RowTimes','st');
should be happy. So there must be something going on with
str.st = mysig(:,1);
str.s1 = mysig(:,2);
T = struct2table(str);
In any case, that seems round-about. I would think
T = array2table(mysig(:,1:2));
would do what you want, but even more directly
TT = timetable(seconds(mysig(:,1)),mysig(:,2))

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Sean de Wolski
Sean de Wolski on 2 May 2020
First column is an array of scalar tables... It is not time. You need to flatten the variables in the table.
Something like T = T{:,:}
How did you create this? Just call readtable or readtimetable directly on your Excel file...
Peter Perkins
Peter Perkins on 5 May 2020
Yes, and in fact it looks like maybe your entire table is made up of cell arrays, each cell containing a 1x1 table? You have gone astray when reading from your Excel file; just use readtimetable or readtable.

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