How to replace a column in a table with different values?

aa is a 1338 x 133 double. The first part of this code averages the data to be 13 x 133. However, I do not want the first column to be averaged. I want it to read 1,2,3,4,5,6,7,8,9,10,11,12,13. I tried to accomplish this by transforming the double into a table and replacing the first column with the numbers I want but I run into this error. Any help on either the first part or the second part of this code would be much appreciated!

Code:
x  = aa;
p  = 100;
n  = size(x, 1);          % Length of first dimension
nc = n - mod(n, p);       % Multiple of p
np = nc / p;              % Length of result
xx = reshape(x(1:nc, :), p, np, []); % [p x np x size(x,2)]
y  = sum(xx, 1) / p;      % Mean over 1st dim
y  = reshape(y, np, []);  % Remove leading dim of length 1

B = array2table(y);

new = ['1'  '2'   '3'   '4'   '5'   '6'   '7'   '8'   '9'   '10'   '11'   '12'   '13'];    % the column to replace column 1 with
 B(:, 1)= new;     % the column to replace column 1 with
 
 Error:
 
 Error using june20code (line 13)
To assign to or create a variable in a table, the number of rows must match the height of the table

Answer 1

[Adam Danz]

You were close. Use curly brakets and input a column vector.

B{:,1} = (1:13).'; 

% or 

B.y1 = (1:13).'; 

Note that the examples above use numbers. If you wanted to use strings or char arrays (as in your example),

new = {'1'  '2'   '3'   '4'   '5'   '6'   '7'   '8'   '9'   '10'   '11'   '12'   '13'}';  
B.y1 = new';

[Julia Williams]

Thank you Adam!

[Adam Danz]

Glad I could help!

[Matthieu Sherwood]

Hi adam!

[Adam Danz]

You found me! :D