Loading Psydat Files Generated from Older PsychoPy Versions

Coding
1

Hi,

I am working on the standalone PsychoPy3 platform and I have been trying to load psydat files generated from PsychoPy version 1.85.1. Running “fromFile(filename)” gives me the following error:

Exception ignored in: <bound method ExperimentHandler.del of <psychopy.data.experiment.ExperimentHandler object at 0x10a9010b8>>
Traceback (most recent call last):
File “/Applications/PsychoPy3.app/Contents/Resources/lib/python3.6/psychopy/data/experiment.py”, line 109, in del
self.close()
File “/Applications/PsychoPy3.app/Contents/Resources/lib/python3.6/psychopy/data/experiment.py”, line 391, in close
if self.dataFileName not in [’’, None]:
AttributeError: ‘ExperimentHandler’ object has no attribute ‘dataFileName’
Traceback (most recent call last):
File path_to_script, line 21, in
datFile = fromFile(filename)
File “/Applications/PsychoPy3.app/Contents/Resources/lib/python3.6/psychopy/tools/filetools.py”, line 55, in fromFile
contents = pickle.load(f)
UnicodeDecodeError: ‘ascii’ codec can’t decode byte 0xd5 in position 0: ordinal not in range(128)

I then tried opening the psydat files after unpickling them using the following:
with open(filename, ‘rb’) as f:
datFile = pickle.load(f, encoding = “latin1”)

However, it seems that this opens the psydat files as an ExperimenterHandler object, rather than a TrialHandler object, so I cannot use commands such as datFile.data to extract the data conveniently. Instead, I have been looping through each trial as a dictionary and appending the trial information to lists, but I would ideally want to avoid this to make sure the code is not skipping through any trials.

I would appreciate your help resolving this issue.

Thank you!

2

a psydat file is literally just a pickle file of either a TrialHandler or an ExperimentHandler. Iit used to be just a TrialHandler but then ExperimentHandler objects became more important (because they can save data from multiple loops or from objects outside a loop) and now all Builder experiments create those instead.

ExperimentHandlers have an attribute loops each of which is a TrialHandler (or StairHandler etc) and you can carry on as before, but there’s also an attribute called entries that provides a list of dicts, one dict for each trial, and this is what is used for ExperimentHandler’s own methods e.g. to save data

3

Hi Jon,

Thank you for explaining about ExperimentHandler objects. I have been using entries but I wanted to avoid manually looping through each trial to extract the relevant information. But with the loops attribute, I started pulling out the information from all trials together. Thank you for pointing it out.

I appreciate your help!