hasdata

Determine if data is available to read

Syntax

tf = hasdata(ds)

Description

tf = hasdata(ds) returns logical 1 (true) if there is data available to read from the datastore specified by ds. Otherwise, it returns logical 0 (false).

example

Examples

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Determine if Data is Available to Read

Open Live Script

Create a datastore from the sample file, mapredout.mat, which is the output file of the mapreduce function.

ds = datastore('mapredout.mat');

While there is data available in the datastore, read the data.

while hasdata(ds)
    T = read(ds);
end

Input Arguments

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`ds` — Input datastore
datastore

Input datastore. You can use these datastores as input to the hasdata method.

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 or transformed datastores — Datastores created using the combine and transform functions.
Custom datastores — Datastores created using the custom datastore framework. See Develop Custom Datastore.

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 hasdata 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 hasdata 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 R2014b