Assigning many cell array entries to same value using index

I would like to use an index to assign many entries in a cell array to the same value, but this example does not work. What should I be doing differently?

%% Goal is cell array 'cellArray' containing 'High' for certain elements, and 'Low' for other elements
% Create the index
a = rand(100, 1); 
iHigh = a > 0.5; % Index to many values
iLow = a <= 0.5; % Index to many other values
% Assign the cell values based on the index
cellArray{iHigh} = 'High';
cellArray{iHigh} = 'Low';
% Gives error
% Assigning to 54 elements using a simple assignment statement is not supported. Consider using
% comma-separated list assignment.
cellArray(iHigh) = 'High';
cellArray(iLow) = 'Low';
% Gives error
% Unable to perform assignment because the indices on the left side are not compatible with the size of
% the right side.

Answer 1

[Image Analyst]

Seems like it should work, but it doesn't. However this works:

%% Goal is cell array 'cellArray' containing 'High' for certain elements, and 'Low' for other elements
% Create the index
a = rand(100, 1); 
cellArray = cell(100, 1); % Initialize cell array
iHigh = a > 0.5; % Index to many values
iLow = a <= 0.5; % Index to many other values
% Assign the cell values based on the index.  
% Put a cell into an element of an array that is a cell.
cellArray(iHigh) = {'High'};
cellArray(iLow) = {'Low'};

[KAE]

Thanks. It even works without initializing cellArray.

Answer 2

[Matt J]

Another way,

[cellArray{iHigh}] = deal('High');
[cellArray{iLow}] = deal('Low');

Answer 3

[Matt J]

You should probably be using strings or catgorical arrays instead of cells. Regardless, it is easy to switch back and forth:

cellArray=string(cellArray);

cellArray(iHigh) = 'High';
cellArray(iLow) = 'Low';

cellArray=cellstr(cellArray);