Different outputs when using { : }

Hi,

I am new to MATLAB and have a very basic question.

Say I have a 2x2 string:

>> str = ["Jan" "Feb"; "Mar" "Apr"]

str = 

  2×2 string array

    "Jan"    "Feb"
    "Mar"    "Apr"
    

Why are the following two different?

str{:};
A = str{:};

Thanks in advance

[Stephen23]

"Why are the following two different?"

Because in one case you allocate to a variable, and in other you don't.

As an aside, using curly-braces on a string array creates a comma-separated list:

https://www.mathworks.com/help/matlab/matlab_prog/comma-separated-lists.html

Note that the comma-separated list constitutes the content of the container array, i.e. character vectors and not string scalars.

Answer 1

[Kevin Holly]

When you used the braces the way you did, it turned the string array into a character array.

I would look at the following:

Text in String and Character Arrays

What is a Cell Array?

[Kevin Holly]

Example:

String Array

str = "test"

str = "test"

Check size

size(str)

ans = 1×2

1 1

Look at first element, it is still a string array

str(1)

ans = "test"

Check size

size(str(1))

ans = 1×2

1 1

Now add braces, it is now a character array

str{1}

ans = 'test'

Check size

size(str{1})

ans = 1×2

1 4

Create Cell Array

{str}

ans = 1×1 cell array
    {["test"]}

Let's create a character array

str = 'test'

str = 'test'

Check size

size(str)

ans = 1×2

1 4

[Stephen23]

@Kevin Holly: so string arrays are really just cell arrays of character vectors?

Otherwise what is the relevance of the page "What is a Cell Array?" ?

[Kevin Holly]

@Stephen Cell arrays can also include numeric values and other arrays. When I first mentioned Daniya's use of braces caused the string array to become a character array, I didn't want Daniya to get confused and think the use of braces will always make a character array. For instance if you place braces around the variable, it creates a cell array. Also, it is good to know the differences. Then I decided to make the above comment to make things clear.