IDL has been buggy in the past for writing .sav` files in the proprietary data format. One should instead save data to NetCDF4 or HDF5.

Read IDL .sav files from Python:

from scipy.io import readsav

data = readsav('mydata.sav')

data

dict() of IDL variables.

My Scipy contribution: IDL was able to read the .sav file, so I wrote a one-off IDL script to convert from IDL .sav to NetCDF4 .NC: sav2nc.pro format. I also have code there to convert from IDL .sav to HDF5.

I also successfully submitted a patch to SciPy to fix some of these IDL .sav reading issues.