Set different row name in table with certain range of rows

Hye, may i know how to set the different row names in table with certain range of rows. i also have a quite big table full with data which is in form of 361x1 table.

Example of my problems:

i want to label A from row 1 until 19, B from row 20 until 39 and it goes on and on until my table has complete row names. The range to set the label is every 19 rows and it change to another label.

Therefore, i hope that somebody can help to solve my problems. I had try to look at documentation in matlab but still confuse and cannot figure it out. I really need your help and it really will be much appreciated. Thank you.

[Ameer Hamza]

In tables, row names cannot be duplicate. Do you want to name them as a1, a2, ...., a19, b1, b2, ...?

[Nurul Atifah]

I want to name them like this structure:

X,y,z| F1 --> 1st row

X,y,z| F1 --> 2nd row

x,y,z| F1 --> 3rd row

And until 19th row it will be F1.

Then, the 20th row until 39th row will be F2 and so on. The range for label to change is same which is every 19.

And before I convert my data array to table, it is in form of 361x83.

[Guillaume]

Again, as Ameer said row names cannot be duplicate.

You cannot have 19 rows with the same name F1. Matlab will not let you.

You could store these names in a column of the table but they would not be row names.

Perhaps you need to explain why you want to give the same name to several rows.

[Stephen23]

If these strings indicate some category membership, then they should really be added as a new variable/column, rather than as a row names.

[Nurul Atifah]

Ohh I see so I need to add another column for it. Ok, now I know enough that table cannot make row names to be duplicate but is it possible if I change back to cell or array and put row names in it or is it just the same as the table? The reason why I want to put the same name because the few row of data that I have is actually in the same category. And I haq quite large data. I need to sort it by rows.

[Guillaume]

if I change back to cell or array and put row names

Neither of these can have names for row duplicate or otherwise. Only tables can have row names.

If it's for categorising the rows, then simply add a new column. Rather than using char arrays or strings, I would recommend you use categorical arrays

Answer 1

[Guillaume]

As we've established you can't use the row name property for labelling your rows but you can just use a new column. To label the new columns in order in group of 19:

labelnumber = repelem((1:ceil(height(yourtable)/20))', 20);
labelnumber = labelnumber(1:height(yourtable));
yourtable.label = compose('label%d', labelnumber);

or even better use categorical arrays instead of char arrays, so replace the last line by

yourtable.label = categorical(compose('label%d', labelnumber));

You can then sortrow by the label column or use rowfun with 'GroupingVariables', 'label' to calculate stats for each group.

P.S.: I've grouped the rows in groups of 20. Your question is ambiguous on the numbers of elements in each group. row 1-19 is 19 rows, but row 20-39 is 20 rows!