Initialising tabular data structure using struct()

For this I'm using an example as below

Eg, A table of data structures, size NL,ML, which has three data types within, at, bt and pt which all have a size nL, mL

Such that all of the below are reasonable:

data(NL,ML).bt(nL,mL) = 5 ;
data(NL-5,ML-2).pt(nL-2,mL-1) = 1 ;

To pre-allocate a data structure like this, I know you need to use struct like below

data = struct(pt,zeros(nL,mL)) ;

However, this creates a data structure that doesn't have the (nL,mL) as above. My current workaround is within the for-loop writing something as below

for N = 1 : NL
for M = 1 : ML
    data(N,M) = struct('at',zeros(nL,mL),'bt',zeros(nL,mL),'pt',zeros(nL,mL)) ;
end
end

However this clearly isn't pre-allocated, as it's adding a new column and row to the first table bit each iteration. How can you pre-allocate a table of data structures like this?

Answer 1

[Stephen23]

A simple REPMAT does the job:

M = zeros(nL,mL);
data = repmat(struct('at',M, 'bt',M, 'pt',M), NL,ML);