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 = tabularTextDatastore('airlinesmall.csv','TreatAsMissing','NA',...
    'SelectedVariableNames',varnames);
tt = tall(ds)

tt =

  Mx2 tall table

    Year    UniqueCarrier
    ____    _____________

    1987       {'PS'}    
    1987       {'PS'}    
    1987       {'PS'}    
    1987       {'PS'}    
    1987       {'PS'}    
    1987       {'PS'}    
    1987       {'PS'}    
    1987       {'PS'}    
     :            :
     :            :

Test whether the underlying data type of the first table variable Year is single.

tf = isaUnderlying(tt.Year,'single')

tf =

  tall logical

   0

Determine the actual underlying data type of Year.

udt = classUnderlying(tt.Year)

udt =

  1x6 tall char array

    'double'