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Tall Arrays

Arrays with more rows than fit in memory

Tall arrays provide a way to work with data backed by a datastore that can have millions or billions of rows. You can create tall numeric arrays, cell arrays, categoricals, strings, datetimes, durations, or calendar durations, and you can use any of these tall types as variables in a tall table or tall timetable. Many operations and functions work the same way with tall arrays as they do with in-memory MATLAB® arrays, but most results are evaluated only when you request them explicitly using gather. MATLAB automatically optimizes the queued calculations by minimizing the number of passes through the data. For more information, see Tall Arrays .

For more information about integrating with big data systems or compiling tall array algorithms, see Extend Tall Arrays with Other Products.

Functions

tallCreate tall array
datastoreCreate datastore for large collections of data
mapreducerDefine execution environment for mapreduce or tall arrays
gatherCollect tall array into memory after executing queued operations
headGet top rows of table, timetable, or tall array
tailGet bottom rows of table, timetable, or tall array
topkrowsTop rows in sorted order
istallDetermine if input is tall array
classUnderlyingClass of underlying data in tall array
isaUnderlyingDetermine if tall array data is of specified class
writeWrite tall array to disk for checkpointing
tallrngControl random number generation for tall arrays

Topics

Tall Arrays

Learn about tall arrays and perform an example calculation.

Functions That Support Tall Arrays (A–Z)

An alphabetical list of MATLAB functions that support tall arrays.

Deferred Evaluation of Tall Arrays

How to leverage deferred execution of tall arrays to optimize performance of calculations.

Index and View Tall Array Elements

Extract, assign, and view portions of a tall array.

Grouped Statistics Calculations with Tall Arrays

This example shows how to use the findgroups and splitapply functions to calculate grouped statistics of a tall timetable containing power outage data.

Visualization of Tall Arrays

Visualization techniques for tall arrays.

Histograms of Tall Arrays

This example shows how to use histogram and histogram2 to analyze and visualize data contained in a tall array.

Extend Tall Arrays with Other Products

List of products that enhance capabilities of tall arrays.

Related Information

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