countEachLabel
Count number of unique labels
Description
counts the number of times each unique label occurs in the datastore. When the datastore
tbl
= countEachLabel(ADS
,'TableVariable',VariableName
)Labels
property is specified by a table, you must specify
VariableName
. VariableName
is the table variable
(column) name you want to count.
Examples
Label Count
Specify the file path to the audio samples included with Audio Toolbox™.
folder = fullfile(matlabroot,'toolbox','audio','samples');
Create an audio datastore that points to the specified folder. Specify the LabelSource
property as foldernames
, so that the label associated with each file is set to the folder name that contains the file.
ads = audioDatastore(folder,'Labelsource','foldernames')
ads = audioDatastore with properties: Files: { ' .../matlab/toolbox/audio/samples/Ambiance-16-44p1-mono-12secs.wav'; ' .../matlab/toolbox/audio/samples/AudioArray-16-16-4channels-20secs.wav'; ' .../toolbox/audio/samples/ChurchImpulseResponse-16-44p1-mono-5secs.wav' ... and 36 more } Folders: { ' .../Bdoc24b.2679053/build/runnable/matlab/toolbox/audio/samples' } Labels: [samples; samples; samples ... and 36 more categorical] AlternateFileSystemRoots: {} OutputDataType: 'double' OutputEnvironment: 'cpu' SupportedOutputFormats: ["wav" "flac" "ogg" "opus" "mp3" "mp4" "m4a"] DefaultOutputFormat: "wav"
Call countEachLabel
to count the number of times each unique label occurs.
tbl = countEachLabel(ads)
tbl=1×2 table
Label Count
_______ _____
samples 39
Label Count when Labels
Is Specified by Table
If the Labels
property of an audio datastore is specified as a table, you must specify the table variable name when counting labels.
Specify the file path to the audio samples included with Audio Toolbox™.
folder = fullfile(matlabroot,'toolbox','audio','samples');
Create an audio datastore that points to the specified folder.
ADS = audioDatastore(folder)
ADS = audioDatastore with properties: Files: { ' .../matlab/toolbox/audio/samples/Ambiance-16-44p1-mono-12secs.wav'; ' .../matlab/toolbox/audio/samples/AudioArray-16-16-4channels-20secs.wav'; ' .../toolbox/audio/samples/ChurchImpulseResponse-16-44p1-mono-5secs.wav' ... and 36 more } Folders: { ' .../Bdoc24b.2679053/build/runnable/matlab/toolbox/audio/samples' } AlternateFileSystemRoots: {} OutputDataType: 'double' OutputEnvironment: 'cpu' Labels: {} SupportedOutputFormats: ["wav" "flac" "ogg" "opus" "mp3" "mp4" "m4a"] DefaultOutputFormat: "wav"
The file names contain information about the files. Parse the file names to collect information about whether a file is mono or stereo and whether a file is longer than thirty seconds. Create a table containing the parsed information and then set the Labels
property of the audio datastore to the label table.
numFiles = numel(ADS.Files); numChannels = cell(numFiles,1); isLong = cell(numFiles,1); for i = 1:numFiles if ~isempty(strfind(ADS.Files{i},'mono')) numChannels{i} = 'mono'; elseif ~isempty(strfind(ADS.Files{i},'stereo')) numChannels{i} = 'stereo'; else numChannels{i} = 'unknown'; end secs = str2double(regexp(ADS.Files{i}, '-(\d+)secs', 'tokens', 'once')); if secs > 30 isLong{i} = true; elseif secs <= 30 isLong{i} = false; else isLong{i} = 'unknown'; end end labelTable = table(numChannels,isLong, ... 'VariableNames',{'NumberOfChannels','IsLongerThan30Seconds'}); ADS.Labels = labelTable;
Call countEachLabel
on the audio datastore and specify the TableVariable
as NumberOfChannels
. Call countEachLabel
and specify the TableVariable
as IsLongerThan30Seconds
.
countNumberOfChannelLabels = countEachLabel(ADS,'TableVariable','NumberOfChannels')
countNumberOfChannelLabels=3×2 table
NumberOfChannels Count
________________ _____
mono 26
stereo 10
unknown 3
countDurationLabels = countEachLabel(ADS,'TableVariable','IsLongerThan30Seconds')
countDurationLabels=3×2 table
IsLongerThan30Seconds Count
_____________________ _____
false 28
true 6
unknown 5
Input Arguments
ADS
— Audio datastore
audioDatastore
object
Specify ADS
as an audioDatastore
object.
VariableName
— Label table variable name
character vector | string
Label table variable name, specified as a character vector or string that
corresponds to a table variable of the Label
property.
This syntax is required if the Label
property of
audioDatastore
is specified by a table.
Data Types: char
| string
Output Arguments
tbl
— Table of label counts
two-column table
Table of label counts, returned as a two-column table containing the name of each
label in ADS
and the number of files associated with each
label.
Data Types: table
Version History
Introduced in R2018b
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