I am getting a CELL2MAT error and dont know why.

I am calling a user-defined python function from matlab and it generates two python tuples, P and Q. I need to extract this data for use in MatLab but when I run my code, I get the error:

"Error using cell2mat (line 52)

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

Here is my code and at the bottom, commented out, is the python module that is being called in MatLab.

runRSK = py.importlib.import_module('RSKAlgPy');
perm = input('Input permutation in the form [a b c ... n]\n');
PQ = runRSK.RSK(perm);
P=PQ(1);
Q=PQ(2);


P1 = cellfun(@(x) cell2mat(cell(x)), cell(P{1}), 'Uniform',false);
P1 = vertcat(P1{:});

Q1 = cellfun(@(x) cell2mat(cell(x)), cell(Q{1}), 'Uniform',false);
Q1 = vertcat(Q1{:});

%% The actual script written in Python

% from bisect import bisect
% def RSK(p):
%     '''Given a permutation p, spit out a pair of Young tableaux'''
%     P = []; Q = []
%     def insert(m, n=0):
%         '''Insert m into P, then place n in Q at the same place'''
%         for r in range(len(P)):
%             if m > P[r][-1]:
%                 P[r].append(m); Q[r].append(n)
%                 return
%             c = bisect(P[r], m)
%             P[r][c],m = m,P[r][c]
%         P.append([m])
%         Q.append([n])
% 
%     for i in range(len(p)):
%         insert(int(p[i]), i+1)
%     return (P,Q)
% 
% print(RSK('43512'))

I think maybe the elements of the py.tuples are not the correct types of elements to use cell2mat but I am not sure how to fix this.

[dpb]

I "know nuthink!" about Python and you don't show us the actual data, but I'm guessing you have a cell which contains a cell array and as the error says, cell2mat can't handle the double dereferencing.

Try removing the cell() cast from the function...you're making a cell array of what ever P is...there's no point in cell(P{1}); you dereference P then turn it back into a cell again...just use P(1) if it is a cell array.

But, we need at a minimum

whos P

to have a clue what you are generating...

[badscience]

I will give that a shot, sorry I didnt include the data, here is an example of what the code generates so far for an input of [1 5 4 3 2 6]:

P = 

  Python tuple with no properties.

    ([[1, 2, 6], [3], [4], [5]],)
    

    whos P
  Name      Size            Bytes  Class       Attributes

  P         1x1                 8  py.tuple              

  
  Q = 

  Python tuple with no properties.

    ([[1, 2, 6], [3], [4], [5]],)
    
    whos Q
  Name      Size            Bytes  Class       Attributes

  Q         1x1                 8  py.tuple      
  
  

The python script runs the RSK algorithm on a given permutation of the symmetric group, i.e. the input is a permutation of some integers 1 through n, and generates two tableaux which are represented by the tuples here. I need to be able to take those tuples and put that data in two separate arrays, one for P, one for Q.

[Walter Roberson]

if P{1} is a java array, then cell(P{1}) returns a cell array with equivalent content, which is a worthwhile thing to do.

If P{1} happened to be a numeric vector then cell(P{1}) would be asking to preallocate a cell with those sizes, which is not equivalent to just leaving P{1} in the cell.