isSubsettable

Determine whether datastore is subsettable

Since R2022b

Syntax

tf = isSubsettable(ds)

Description

tf = isSubsettable(ds) returns logical 1 (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 as TransformedDatastore, CombinedDatastore, and SequentialDatastore, are subsettable only when all underlying datastores are subsettable.

Examples

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

Subset successful.

Input Arguments

ds — Input datastore

datastore

Input datastore. You can use these datastores as input:

• MATLAB^® datastores — Datastores created using MATLAB datastore 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, or TransformedDatastore objects you create from ImageDatastore objects by using combine 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 either ProcessPool or ClusterPool).

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

Version History

Introduced in R2022b