readall

R2026b

Read all signals from datastore

The function has changed. For more information, see Version History.

Syntax

data = readall(sds)

data = readall(sds,UseParallel=par)

Description

data = readall(sds) reads all signal data from the datastore sds.

data = readall(sds,UseParallel=par) enables you to read data in parallel. (since R2026a)

To read data in parallel, you must have a Parallel Computing Toolbox™ license and create the signalDatastore object sds using file data.

Examples

Read and Analyze All Signals in Signal Datastore

Specify the path to four signals included with MATLAB®. The signals are recordings of a bird chirp, a gong, a train, and a splat. All signals are sampled at 8192 Hz.

folder = fullfile(matlabroot,"toolbox","matlab","audiovideo", ...
         ["chirp.mat","gong.mat","train.mat","splat.mat"]);
Fs = 8192;
sds = signalDatastore(folder,SampleRate=Fs);

Read the data in the first variables of all the files in the datastore and plot the Fourier synchrosqueezed transform of each signal.

data = readall(sds);

tiledlayout("flow")
for i = 1:length(data)
    nexttile
    fsst(data{i},Fs,"yaxis")
end

Input Arguments

sds — Signal datastore

signalDatastore object

Signal datastore, specified as a signalDatastore object.

par — Option to read data in parallel

"off" (default) | "auto" | "on"

Option to read data in parallel using a pool of workers, specified as one of these values:

• "off" — Read data serially on the MATLAB^® client.

• "auto" — Read data using a parallel pool if one is open or if MATLAB can automatically create one. If a parallel pool is not available, read data serially on the MATLAB client.

• "on" — Read data using a parallel pool if one is open or if MATLAB can automatically create one. If a parallel pool is not available, throw an error.

If you do not have a parallel pool open and automatic pool creation is enabled, MATLAB opens a pool using the default cluster profile. To use a parallel pool to run computations in MATLAB, you must have Parallel Computing Toolbox. For more information, see Run MATLAB Functions with Automatic Parallel Support (Parallel Computing Toolbox).

Note

Parallel reading is supported only if you create the signalDatastore object sds using file data.

Before R2026b: To run in parallel, set this argument to true (1).

Data Types: char | string

Output Arguments

data — All signals in signal datastore

cell array

All signals in the signal datastore, returned as a cell array. Each cell of data contains signals from a file or a member. Use the ReadOutputOrientation property of the datastore to control the orientation of data as either a column array or a row array.

Tips

When reading file data, because this function reads all the data in the files at once, you may run out of memory if your data set is large.

Extended Capabilities

Automatic Parallel Support

Accelerate code by automatically running computation in parallel using Parallel Computing Toolbox™.

The readall function has automatic parallel support. To run computations in parallel, set the UseParallel argument to "on" or "auto".

For more information, see Run MATLAB Functions with Automatic Parallel Support (Parallel Computing Toolbox).

Version History

Introduced in R2020a

R2026b: Enhanced control over parallel execution with UseParallel argument

The UseParallel name-value argument now accepts "off", "auto", or "on" values instead of true or false. This change gives you more control over when to use a parallel pool.

Specifying the UseParallel name-value argument as true or false is not recommended. This table shows how to update your code.

Goal	Name-Value Argument in R2026a or Earlier	Updated Name-Value Argument in R2026b
Read data serially on the MATLAB client.	UseParallel=false	UseParallel="off" (default)
Read data using a parallel pool or, if a pool is not available, read data serially on the MATLAB client.	UseParallel=true	UseParallel="auto"
Read data using a parallel pool or, if a pool is not available, error out.	N/A	UseParallel="on"

R2026a: Read data in parallel

The UseParallel name-value argument in the readall function enables you to read data in parallel. You must have a Parallel Computing Toolbox license to use this functionality.