partition - Partition label datastore - MATLAB (original) (raw)

Partition label datastore

Syntax

Description

[subds](#buouv0l-1-subds) = partition([ds](#mw%5Ff81ee525-4ced-4568-b110-24841f1b997b),[N](#buouv0l-1-N),[index](#buouv0l-1-index)) partitions a datastore ds into N parts and returns the partition corresponding to index.

example

[subds](#buouv0l-1-subds) = partition([ds](#mw%5Ff81ee525-4ced-4568-b110-24841f1b997b),'Files',[fileIndex](#mw%5F445d8729-f8e8-40f1-947a-62f2a6865c7e)) partitions the PixelLabelDatastore by files. The partitioned datastore corresponds to the index in theFiles property of the datastore.

[subds](#buouv0l-1-subds) = partition([ds](#mw%5Ff81ee525-4ced-4568-b110-24841f1b997b),'Files',[filename](#buouv0l-1-filename)) partitions the PixelLabelDatastore by files. The partitioned datastore corresponds to the file specified byfilename.

Examples

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Load training data that contains bounding boxes with labels for vehicles.

data = load('vehicleTrainingData.mat'); trainingData = data.vehicleTrainingData; blds = boxLabelDatastore(trainingData(:,2:end));

Use the partition function to partition the box label datastore. The output contains the first 5 rows of the training data.

subds = partition(blds,59,5);

Read the data. Use the hasdata function to check for data.

while hasdata(subds) % Read one row of box labels at a time bxLabels = read(subds); end

Input Arguments

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Number of partitions to divide datastore, specified as a positive integer. To obtain an estimate for a reasonable number of partitions, use thenumpartitions function.

numWorkers = 3; p = parpool('local',numWorkers); n = numpartitions(ds,p);

parfor ii=1:n subds = partition(ds,n,ii); while hasdata(subds) data = read(subds); end end

Example: 3

Data Types: double

Index, specified as an integer. The index points to a partitioned datastore of the N number of partitioned datastores.

Example: 1

Data Types: double

File index of a file stored within the Files property of a pixelLabelDatastore, specified as a positive integer.

Example: 1

Data Types: double

Filename, specified as a character vector.

Example: 'file1.csv'

Example: '../dir/data/file1.csv'

Example: 'hdfs://myserver:7867/data/file1.txt'

Data Types: char

Output Arguments

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Output datastore, returned as a datastore object. The output datastore is of the same type as the input datastore, ds.

Version History

Introduced in R2017b