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hasNextBlock

Determine if blocked file-set has another block

Since R2020a

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Syntax

tf = hasNextBlock(bs)

Description

tf = hasNextBlock(bs) returns logical 1 (true) if another block is available to process in the BlockedFileSet object specified by bs. Otherwise, it returns logical 0 (false).

example

Examples

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Open Live Script

Check if a blocked file-set has another block available to process and read the data iteratively.

Create a blocked file-set bs for a collection of files.

folder = {'accidents.mat','airlineResults.mat','census.mat','earth.mat'}
folder = 1x4 cell
    {'accidents.mat'}    {'airlineResults.mat'}    {'census.mat'}    {'earth.mat'}


bs = matlab.io.datastore.BlockedFileSet(folder)
bs = 
  BlockedFileSet with properties:

                   NumBlocks: 4
               NumBlocksRead: 0
                   BlockSize: 'file'
                   BlockInfo: BlockInfo for all 4 blocks
    AlternateFileSystemRoots: {}

Use the hasNextBlock and nextblock functions to read block information one block at a time while blocks remain in the set.

while hasNextBlock(bs)
   file = nextblock(bs)
end
file = 
  1x1 BlockInfo
                                                        Filename                                                         FileSize    Offset    BlockSize
    _________________________________________________________________________________________________________________    ________    ______    _________

    "/mathworks/devel/bat/filer/batfs2566-0/Bdoc24b.2725827/build/runnable/matlab/toolbox/matlab/demos/accidents.mat"      7343        0         7343   



file = 
  1x1 BlockInfo
                                       Filename                                        FileSize     Offset    BlockSize 
    ______________________________________________________________________________    __________    ______    __________

    "/tmp/Bdoc24b_2725827_1770503/tpc95639c5/matlab-ex12893120/airlineResults.mat"    1.5042e+05      0       1.5042e+05



file = 
  1x1 BlockInfo
                                                       Filename                                                       FileSize    Offset    BlockSize
    ______________________________________________________________________________________________________________    ________    ______    _________

    "/mathworks/devel/bat/filer/batfs2566-0/Bdoc24b.2725827/build/runnable/matlab/toolbox/matlab/demos/census.mat"      353         0          353   



file = 
  1x1 BlockInfo
                                                      Filename                                                       FileSize    Offset    BlockSize
    _____________________________________________________________________________________________________________    ________    ______    _________

    "/mathworks/devel/bat/filer/batfs2566-0/Bdoc24b.2725827/build/runnable/matlab/toolbox/matlab/demos/earth.mat"     32522        0         32522  



Input Arguments
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Blocked file-set, specified as a matlab.io.datastore.BlockedFileSet object. To create a BlockedFileSet object, see matlab.io.datastore.BlockedFileSet.

          
Example: hasNextBlock(bs)

        
Version History
Introduced in R2020a
See Also
Topics