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%% Determine Underlying Class of Tall Arrays % All tall tables and arrays belong to the |tall| class. However, the % _underlying_ data type of a tall array can vary. % % Create a datastore for the |airlinesmall.csv| data set. Select a subset % of the variables to work with, and treat |'NA'| values as missing data so % that |datastore| replaces them with |NaN| values. Convert the datastore % into a tall table. varnames = {'Year', 'UniqueCarrier'}; ds = datastore('airlinesmall.csv','TreatAsMissing','NA',... 'SelectedVariableNames',varnames); tt = tall(ds) %% % Determine the class of the tall table |tt| and the first table variable % |Year|. class(tt) %% class(tt.Year) %% % Determine the underlying data types of |tt|, as well as the |Year| and % |UniqueCarrier| table variables. classUnderlying(tt) %% classUnderlying(tt.Year) %% classUnderlying(tt.UniqueCarrier) %% % In some cases, the result returned by |classUnderlying| is an unevaluated % tall array. Unevaluated tall arrays can be evaluated using the |gather| % function to bring the result into memory.