hasPreviousBlock

Determine if blocked file-set has previous block

Description

example

tf = hasPreviousBlock(bs) returns logical 1 (true) if any previous blocks are available to process in the BlockedFileSet object specified by bs. Otherwise, it returns logical 0 (false).

Examples

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Check if a blocked file-set has a previous block available to process.

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

folder = {'accidents.mat','airlineResults.mat','census.mat','earth.mat'}
folder = 1x4 cell
  Columns 1 through 3

    {'accidents.mat'}    {'airlineResults...'}    {'census.mat'}

  Column 4

    {'earth.mat'}

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

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

Get the information for the first block and move the internal pointer forward one block.

blk1 = nextblock(bs)
blk1 = 
  1x1 BlockInfo
                                       Filename                                       FileSize    OffSet    BlockSize
    ______________________________________________________________________________    ________    ______    _________

    "/mathworks/devel/bat/Bdoc20a/build/matlab/toolbox/matlab/demos/accidents.mat"      7343        0         7343   

Get information for the second block and move the internal pointer forward one block.

blk2 = nextblock(bs)
blk2 = 
  1x1 BlockInfo
                                         Filename                                           FileSize     OffSet    BlockSize 
    ___________________________________________________________________________________    __________    ______    __________

    "/mathworks/devel/bat/Bdoc20a/build/matlab/toolbox/matlab/demos/airlineResults.mat"    1.5042e+05      0       1.5042e+05

Check to see if a previous block exists. In this case, the result is true because a previous block exists.

tf = hasPreviousBlock(bs)
tf = logical
   1

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: hasPreviousBlock(bs)

Introduced in R2020a