issue loading case9241pegase

[nesnoj]

The pickle of case case9241pegase seems to be broken in develop branch as

import pandapower.networks as pn
net = pn.case9241pegase()

throws

Traceback (most recent call last):
  File "xxx/python/pypower/pandapower_case2869pegase_opf_test.py", line 10, in <module>
    net = pn.case9241pegase()
  File "xxx/git-repos/pandapower/pandapower/networks/power_system_test_cases.py", line 596, in case9241pegase
    case9241pegase = pp.from_pickle(os.path.join(_get_cases_path(), "case9241pegase.p"))
  File "xxx/git-repos/pandapower/pandapower/file_io.py", line 187, in from_pickle
    net = read(f)
  File "xxx/git-repos/pandapower/pandapower/file_io.py", line 178, in read
    return pickle.load(f, encoding='latin1')
_pickle.UnpicklingError: could not find MARK

[FlorianShepherd]

In my setup (Windows 7 / Ubuntu Linux 64bit, Python 3.6, Anaconda 4.3) it works.

"could not find MARK" sound like a unpickling error. I checked my version with "pickle.format_version" and it is 4.0

Maybe this is the problem? Which version are you using?

[nesnoj]

On a fresh pp install (v1.4.0) in a virtualenv it works fine! But using the manual install of the cloned pp-repo with pip3 (using "-e" Option) I get the described exception in the master as well as in the develop branch. Since the versions of all installed packages equal (including pickle v4.0), the issue might be related to recent modifications of pp?! I run Python 3.5.3 on Xubuntu 17.04.

[ascheidl]

This might indeed be a reason.

However, as soon as I find some time I will alter the storage format of the included networks from pickle to json or sqlite anyways.

These formats are faster and smaller.

[nesnoj]

Ok. Update: The case9241pegase.p files of both versions are different (says MD5).. I will simply use the file from the current stable..