MATLAB: “ismember” error with tall arrays

tallarrays ismember error

I am using Matlab R2016b version and working with tall arrays. I have created a tall table and have also an in-memory cell array, lets' call it B.
I would like to keep only rows of my tall table where tt.Variable1 is found in the in-memory array B.
Thus, I am using function ismember, which is said to work with tall (https://nl.mathworks.com/help/matlab/import_export/functions-that-support-tall-arrays-a-z.html), quoting from the link: Input A must be a tall array, and input B must be an in-memory array. when I do
  1. idx= ismember(tt.Variable1, B)==1;
  2. tt = tt(idx,:);
I get an error: Input A of class tall and input B of class cell must be the same class, unless one is double.
How can I solve this?
SMALL EDIT: For more informatioin:
  • class(B)=cell
  • class(tt.Variable1)=tall
  • classUnderlying(tt.Variable1)=
  • 1×4 tall char array
  • cell

Best Answer

tall/ismember was only added in R2017a. See the R2016b list of supported functions if you cannot upgrade to R2017a. In R2017a, you can do stuff like this:
>> tt = tall(table({'a'; 'b'; 'c'; 'd'; 'e'}, rand(5, 1)))
tt =
  5×2 tall table
    Var1     Var2  
    ____    _______
    'a'     0.15761
    'b'     0.97059
    'c'     0.95717
    'd'     0.48538
    'e'     0.80028
>> B = {'c'; 'e'};
>> idx = ismember(tt.Var1, B);
>> tt(idx,:)
ans =
  2×2 tall table
    Var1     Var2  
    ____    _______
    'c'     0.95717
    'e'     0.80028
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