how to get the column names of one matrix and assign nan to them

A=[A1,A2] ;

where A, A1,A2 are tables

I want to build matrix B such as:

B=[B1,A2];

but this time A2 is the same as A2 above but with nan values;

A2 is 300 columns and assigning the names column by column is a tedious thing to do .

Any help is appreciated

[Stephen23]

What is B1 ?

Where are the column names defined?

How are you creating the tables?

[Danielle Leblance]

B1 is another table that has the same size of A1 but with different variables

B1, A1, and A2 are imported from excel. The column names are automatically imported.

[Image Analyst]

It's easier for us to try things and to help you if you attach your workbook and the code to read it in.

[Bob Thompson]

If all you want is to have an array A2, that is the size of the original A2, but is a bunch of NaN, you should be able to say:

A3 = A2;
A3(:,:) = NaN;

That should get the size of A2 by copying, and then assign all members to be NaN.