Convert cell array of string arrays to a single string array

Say I have a cell array defined as follows:

my_cell = cell(5,1);
% Assign some values
my_cell{1} = "event A";
my_cell{3} = ["event B";"event A";"event C"];
my_cell{4} = ["event C";"event A"];

I want to transform the cell array to a single column of strings = ["event A";"event B";"event A";"event C";"event C";"event A"]. It seems like cell2mat should work for this, but it gives an error:

>> cell2mat(my_cell)

Error using cell2mat

All contents of the input cell array must be of the same data type.

Even if I replace the empty cells with "", it still gives an error:

>> my_cell{2} = "";

>> my_cell{5} = "";

>> cell2mat(my_cell)

Error using cell2mat

CELL2MAT does not support cell arrays containing cell arrays or objects.

In the actual application, each string could have any length, and the resulting vector will have ~10^6 strings. I could obviously just loop over the cell array and construct my string array that way, but this is something I would expect there to be quick 1-line solution for.

Also, since there is just a small set of possible string values, I could also just encode them as numbers, since the following works fine.

my_cell = cell(5,1);
% Assign some values
my_cell{1} = 1;
my_cell{3} = [2;1;3];
my_cell{4} = [3;1];
my_vector = cell2mat(my_cell)

my_vector = 6×1

1 2 1 3 3 1

But in my actual program, I would rather keep my data encoded as strings since it's easier to understand the code that way.

Is there a nice solution for this?

[Stephen23]

"Is there a nice solution for this?"

Yes:

https://www.mathworks.com/matlabcentral/answers/1656435-tutorial-comma-separated-lists-and-how-to-use-them

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

Answer 1

[Paul]

Hi Charles

Use vertcat with a comma separated list as the input

my_cell = cell(5,1);
% Assign some values
my_cell{1} = "event A";
my_cell{3} = ["event B";"event A";"event C"];
my_cell{4} = ["event C";"event A"];


s = vertcat(my_cell{:})

s = 6×1 string array
    "event A"
    "event B"
    "event A"
    "event C"
    "event C"
    "event A"

[Charles]

Perfect! Thank you