How to shuffle fileDatastore

Question

Haoqing Li 2020-6-18

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https://ww2.mathworks.cn/matlabcentral/answers/550882-how-to-shuffle-filedatastore

评论： dpb 2020-7-14

Hi,

I tried to shuffle fileDatastore, but failed.

Any method how to do it?

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Answer 1

Ayush Laddha 2020-6-19

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https://ww2.mathworks.cn/matlabcentral/answers/550882-how-to-shuffle-filedatastore#answer_453799

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I understand that you wish to shuffle the fileDatastore. You can utilize the shuffle function to do so. You can use it as given below –

fs = fileDatastore(path, 'ReadFcn', @load) 
shuffled_fs = shuffle(fs) 

Link to its documentation –

https://in.mathworks.com/help/matlab/ref/matlab.io.datastore.shuffleable.shuffle.html

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Haoqing Li 2020-6-19

编辑：dpb 2020-7-14

在 MATLAB Online 中打开

Hi,

It doesn't work, below is my result:

>>fs = fileDatastore('try', 'ReadFcn', @load )
fs = 
  FileDatastore with properties:
                       Files: {
                              'D:\Google Drive\MultiLayerPerceptron\try\output.mat';
                              'D:\Google Drive\MultiLayerPerceptron\try\output1.mat';
                              'D:\Google Drive\MultiLayerPerceptron\try\output2.mat'
                              }
                     Folders: {
                              'D:\Google Drive\MultiLayerPerceptron\try'
                              }
                 UniformRead: 0
                    ReadMode: 'file'
                   BlockSize: Inf
                  PreviewFcn: @load
      SupportedOutputFormats: ["txt"    "csv"    "xlsx"    "xls"    "parquet"    "parq"    "png"    "jpg"    "jpeg"    "tif"    "tiff"    "wav"    "flac"    "ogg"    "mp4"    "m4a"]
                     ReadFcn: @load
    AlternateFileSystemRoots: {}
    >> shuffled_fs = shuffle(fs);
Check for missing argument or incorrect argument data type in call to function 'shuffle'.
 
>> dsrand = isShuffleable(fs)
dsrand =
  logical
   0

It shows that the filedatastore is not shuffleable, is there any way to make it shuffeable?

Haoqing Li 2020-7-1

Hi,

I'm using 2020a.

dpb 2020-7-14

在 MATLAB Online 中打开

I get same error on R2019b as does Haoqing LI (another poster just asked same Q? and this thread showed up in the automated links system so came to investigate).

Dunno' what is different w/ the release Ayush Laddha used, but

>> ds=fileDatastore('3*.xlsx','ReadFcn',@readtable)
ds = 
  FileDatastore with properties:
                       Files: {
                              'C:\Users\...\Documents\MATLAB\Work\3-15-17.xlsx';
                              'C:\Users\...\Documents\MATLAB\Work\3-16-17.xlsx';
                              'C:\Users\...\Documents\MATLAB\Work\3-17-17.xlsx'
                              }
                 UniformRead: 0
                    ReadMode: 'file'
                   BlockSize: Inf
                  PreviewFcn: @readtable
                     ReadFcn: @readtable
    AlternateFileSystemRoots: {}
>> ds=shuffle(ds)
Undefined function 'shuffle' for input arguments of type 'matlab.io.datastore.FileDatastore'. 
>> 