Python saved .mat file vs. Matlab saved.mat file

I used io.savemat to save dictionary in Python into a .mat file that can be processed in Matlab. The file size is 915 MB. Then I imported the .mat file into matlab and save all variables again in Matlab as another .mat file.Suprisingly, the file size came down to 234 MB, which is much less compared with 915 MB. I thought I lost the precision when did the save in Matlab but I found out no precision was lost after doing subtraction of variables from the two versions of .mat files. I am very curious. Could someone help to explain why?Thanks in advance!

Answer 1

[Walter Roberson]

MATLAB has multiple ways of saving files. In some of them, lossless data compression might happen.