Convert a cell containing structs into a single Struct

I am looking for a less convoluted way of changing a cell array that contains structs and empty arrys in a random order, into a sinlge struct.

I have a cell that contains the structs with similar fileds and empty cell elements in any random order as follows:

s1 = struct('a',1, 'b',2, 'c',3);
s2 = struct('a',10,'b',20,'c',30);
mycell = {[],s1,s2,[]}

mycell = 1x4 cell array
    {0x0 double}    {1x1 struct}    {1x1 struct}    {0x0 double}

I want to convert this cell into a struct that would look like this:

s = struct('a',{}, 'b',{}, 'c',{});
s(2) = s1;
s(3) = s2;
s(4) = struct('a',[], 'b',[], 'c',[]);

the way I am thinking of doing this is:

% first check which cell element conntaians a struct
for ii = 1:length(mycell)
    if isa(mycell{ii},'struct')
        fname = fieldnames(mycell{ii});
        break
    end
end
aa= sprintf('''%s'',{},',fname{:});
aa(end) = '';
S = eval(strcat('struct(',aa,')'));
for ii = 1:length(mycell)
    if isa(mycell{ii},'struct')
        S(ii) = mycell{ii};
    else 
        aa= sprintf('''%s'',[],',fname{:});
        aa(end) = '';
        S(ii) = eval(strcat('struct(',aa,')'));
    end
end

isequal(S, s)

ans = logical
   1

Answer 1

[Stephen23]

Avoid evil EVAL(). Constructing text that looks like code and then evaluating it should definitely be avoided.

Using comma-separated lists would be much much better:

https://www.mathworks.com/matlabcentral/discussions/tips/847976-tutorial-comma-separated-lists-and-how-to-use-them

Using your fake data:

s1 = struct('a',1, 'b',2, 'c',3);
s2 = struct('a',10,'b',20,'c',30);
mycell = {[],s1,s2,[]}

mycell = 1x4 cell array
    {0x0 double}    {1x1 struct}    {1x1 struct}    {0x0 double}

Here is a much better approach based on CELL2STRUCT():

idx = ~cellfun('isempty',mycell);
tmp = [mycell{idx}]; % ensures identical fieldnames
fnm = fieldnames(tmp);
out = cell2struct(cell(numel(mycell),numel(fnm)),fnm,2);
out(idx) = tmp

out = 4x1 struct array with fields:
    a
    b
    c

Checking:

out.a

ans =
     []

ans = 1

ans = 10

ans =
     []

out.b

ans =
     []

ans = 2

ans = 20

ans =
     []

out.c

ans =
     []

ans = 3

ans = 30

ans =
     []

[ROYGBIV]

Thank you, this is very effiecient.