isSubsettable - Determine whether datastore is subsettable - MATLAB (original) (raw)

Determine whether datastore is subsettable

Since R2022b

Syntax

Description

tf = isSubsettable([ds](#mw%5Fb0ade1fd-6df2-4f6d-95bd-cd80b75e0299)) returns logical1 (true) if the datastore is able to be subsetted. If the datastore is not subsettable, the result is logical 0 (false). Datastores containing underlying datastores, such asTransformedDatastore, CombinedDatastore, andSequentialDatastore, are subsettable only when all underlying datastores are subsettable.

example

Examples

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Test If Datastore Is Subsettable

Create an image datastore for the image files in a sample folder. Then, write an if/else statement that subsets the datastore only if it is subsettable.

folders = fullfile(matlabroot,"toolbox","matlab",["demos",fullfile("matlab_images",["png","tiff"])]); exts = [".jpg",".png",".tif"]; imds = imageDatastore(folders,"LabelSource","foldernames","FileExtensions",exts);

Write an if/else statement that subsets the datastore only if it is subsettable.

if isSubsettable(imds) newds = subset(imds,2); disp("Subset successful.") else disp("Datastore is not subsettable.") end

Input Arguments

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ds — Input datastore

datastore

Input datastore. You can use these datastores as input:

• MATLAB® datastores — Datastores created using MATLABdatastore functions. For example, create a datastore for a collection of images using ImageDatastore. For a complete list of datastores, see Select Datastore for File Format or Application.
• Combined, sequential, and transformed datastores — Datastores created using the combine and transform functions.
• Custom datastores — Datastores created using the custom datastore framework. Any datastore that is a subclass of matlab.io.Datastore supports the isSubsettable function. See Develop Custom Datastore for more information.

Extended Capabilities

Thread-Based Environment

Run code in the background using MATLAB® backgroundPool or accelerate code with Parallel Computing Toolbox™ ThreadPool.

Usage notes and limitations:

• In a thread-based environment, you can use isSubsettable only with the following datastores:
  • ImageDatastore objects
  • CombinedDatastore, SequentialDatastore, orTransformedDatastore objects you create fromImageDatastore objects by usingcombine or transform
    You can use isSubsettable with other datastores if you have Parallel Computing Toolbox™. To do so, run the function using a process-backed parallel pool instead of using backgroundPool or ThreadPool (use eitherProcessPool or ClusterPool).

For more information, see Run MATLAB Functions in Thread-Based Environment.

Version History

Introduced in R2022b