How to assign a column of text string to another variable?

For example,

A = repmat('test', 5,1);

If I want to assign A to B, why the below doesn't work? What is the right way to do it?

B([20+1:20+5,1) = A

Many thanks,

[Adam Danz]

What is B? A char array? A string array? A cell array?

[Leon]

It should be a N by 1 column of all the accumulated strings.

I would have A1, A2, A3, ..., etc. I want to combine them into one string B. So B should be identical to A in terms of what kind of array it is, e.g., string or char, etc. Sorry I'm not familiar with the difference between string vs char.

I defined B as

B = NaN (100000,1);

Is that problematic?

[Adam Danz]

You can use class(var) to determine the class of a variable var.

[Adam Danz]

Yes, it's problematic. Your definition of B creates a double precision numeric vector. But A is a char array.

Perhaps you're looking for

% Cell array of chars
A = repmat({'test'}, 5,1);
B = cell(100000,1); 
B([20+1:20+5]) = A; 

or

% String array
A = repmat("test", 5,1);
B = repmat("", 100000,1)
B([20+1:20+5]) = A; 

[Leon]

Thank you! How do I define a N by 1 column of strings or chars?

[Leon]

Thank you so much. It works

The string array is what I need!

Answer 1

[Guillaume]

A = repmat('test', 5,1);

replicates the 1x4 char array 'test' 5 times along the rows, resulting in a 5x4 matrix of 20 characters

B([20+1:20+5,1) = A

attemps to store these 20 characters at indices 21 to 25 of row 1 of B. That's room for just 5 characters, so yes it's not going to work.

Note that you're working with char vectors, not string arrays. Perhaps you intended to work with string arrays. char vectors and string arrays work differently. Your code would work with string arrays. string arrays use ", not ' as the enclosing symbol:

%this would work. No idea if that's what you want
A = repmat("test", 5, 1);  
B(20+(1:5), 1) = A;

However, note that you don't even need the repmat in the above. Assigning a scalar to a vector automatically replicates the scalar:

A = "test";
B(20+(1:5), 1) = A;

[Leon]

Thanks!

Unfortunately, when I test it, my 21 to 25 rows are NaNs.

0
     0
     0
     0
     0
     0
     0
     0
     0
     0
     0
     0
     0
     0
     0
     0
     0
     0
     0
     0
   NaN
   NaN
   NaN
   NaN
   NaN

[Guillaume]

If you're using strings, then B needs to be a string array to starts with. If it's starts as a numerical array then yes the strings will be converted to numbers and "test" not being a valid representation of a number gets converted to NaN (Not a Number).

B = strings(0);
%or
B = string.empty

would create an empty string array. Alternatively,

clear B
A = "test";
B(20+(1:5), 1) = A;

also works.