How to shuffle fileDatastore

Hi,

I tried to shuffle fileDatastore, but failed.

Any method how to do it?

Answer 1

[Ayush Laddha]

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

[Haoqing Li]

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?

[Ayush Laddha]

Hi,

It works perfectly fine for me. I am not able to reproduce the issue you are facing. It would be great if you could provide more info about the MATLAB version you are using?

[Haoqing Li]

Hi,

I'm using 2020a.

[dpb]

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'. 
>>