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%% Write and Reconstruct Tall Array % Write a tall array to disk, then subsequently recover the tall array by % creating a new datastore for the written files. This process is useful to % save your work or share a tall array with a colleague. %% % Create a datastore for the |airlinesmall.csv| data set. Select only the % |Year|, |Month|, and |UniqueCarrier| variables, and treat |'NA'| values % as missing data. Convert the datastore into a tall table. ds = datastore('airlinesmall.csv'); ds.TreatAsMissing = 'NA'; ds.SelectedVariableNames = {'Month','Year','UniqueCarrier'}; tt = tall(ds) %% % Sort the data in descending order by year and extract the top 25 rows. % The resulting tall table is unevaluated. tt_new = topkrows(tt,25,'Year') %% % Save the results to a new folder named |ExampleData| on the |C:\| disk. % (You might want to specify a different write location, especially if you % are not using a Windows(R) computer.) The |write| function evaluates the % tall array prior to writing the files, so there is no need to use the % |gather| function prior to saving the data. location = 'C:\ExampleData'; write(location,tt_new) %% % Clear |tt| and |ds| from your working directory. To recover the tall % table that was written to disk, first create a new datastore that % references the same directory. Then convert the datastore into a tall % table. Since the tall table was evaluated before being written to disk, % the display now includes a preview of the values. clear tt ds ds2 = datastore(location); tt2 = tall(ds2)