unable to load mat file which was saved in python as savemat (at version 7.3) in 2021a matlab.

I have a mat file which was created in python using savemat at version 7.3. The data is perfectly loading in matlab version 2017a but when i tried in version 2021a it is throwing this error "Not a binary MAT-file. Try load -ASCII to read as text". There is no problem with the data, I checked it with matlab version 2017a. Everytime the same file is loading in 2017 but not in 2021.

[dpb]

Can only blame that on Python library function methinks. Nothing in the MATLAB contract says it has to be interactive with other software products.

Attach the .mat file here (or another with same symptom of random data if were some reason not to use the original).

Workaround if you can read with R2017a is to read it there and rewrite a .mat file with R2017a and read it with the later release. If that fails, then you do have something to complain about - or have uncovered a bug in R2021a for the release you're using -- which would be something to try also--ensure you've installed any more recent releases.

[shouvik dey]

Sorry but mat file can't be shared and the problem is with that data or that type of data structure only. I am saying this because i created a random mat file with version 7.3 and matlab 2021 is able to read but when i recreated my original file in matlab 2017 with version 7.3, I could not read that file in matlab 2021. When i saved that file in matlab 2017 with version 7, It was readable in matlab 2021.

I thing some settings issue might be there.

[dpb]

" but when i recreated my original file in matlab 2017 with version 7.3, I could not read that file in matlab 2021."

Are you saying an all-MATLAB file from R2017b couldn't be read by R2021b?

If that is so w/o any Python utilities in the mix, that seems an issue; again if Python is involved I don't think you can blame that on TMW/MATLAB.

The content of the file may not be shared, but if it is related to a structure in a .mat file, you could certainly create the same structure with random data that could be shared.

But, we need more definitive description include actual code that can create the problem; simply descriptions and "doesn't work" isn't sufficient with which to do any debugging.

[Al Danial]

If it's any consolation, I have no difficulty reading Python-created .mat files in 2022a. Here's Python code I used to test:

!/usr/bin/env python
from scipy.io import savemat
import numpy as np
a1 = np.array([5441, 32207], dtype=np.uint16)
a2 = np.array([[0.2785, 0.9575, 0.1576],
               [0.5469, 0.9649, 0.9706]])
b = [ 'this is a', "list", 5+6j ]
c = { 'x' : -17.6, 'y' : 4.98 }
M = {}
M['a1'] = a1
M['a2'] = a2
M['b'] = b
M['c'] = c
savemat('by_python.mat', M)

which loads fine into MATLAB:

>> load by_python
>> whos
  Name      Size            Bytes  Class                                Attributes
  Im        1x1                32  function_handle                                
  a1        1x2                 4  uint16                                         
  a2        2x3                48  double                                         
  ans       1x1                 8  matlab.pyclient.PythonEnvironment              
  b         3x64              384  char                                           
  c         1x1               352  struct                                         
>> a1
a1 =
  1x2 uint16 row vector
    5441   32207
>> a2
a2 =
    0.2785    0.9575    0.1576
    0.5469    0.9649    0.9706
>> b
b =
  3x64 char array
    'this is a                                                       '
    'list                                                            '
    '(5+6j)                                                          '
>> c
c = 
  struct with fields:
    x: -17.6000
    y: 4.9800

This is with Python version 3.8.8.