All tall tables and arrays belong to thetallclass. However, theunderlying数据type of a tall array can vary.

Create a datastore for theairlinesmall.csv数据set. Select a subset of the variables to work with, and treat'NA'values as missing data so that数据storereplaces them withNaNvalues. Convert the datastore into a tall table.

varnames = {“年”,'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 variableYearissingle.

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

tf = tall logical 0

Determine the actual underlying data type ofYear.

udt = classUnderlying(tt.Year)

udt = 1x6 tall char array 'double'