data format problem when using mne.grand_average

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Hello MNE experts,

I tried to aggregate evoked data across subjects and feeded them into
function mne.grand_average. Although I am pretty sure that all elements in
the list are evoked data (see attached photo), it complained about " Not
all input elements are Evoked or AverageTFR".

Here is what I did:

# create place holder
for exp in exps:
            locals()["evoked_"+exp]=[]

# put evoked data from all subjects in the place holder
for exp in exps:
for subj in subjs:
s = mne.read_evokeds("evoked_"+exp+"_"+subj+"-ave.fif")
                locals()["evoked_"+exp].append(s)

# do grand avrage
for exp in exps:
     locals()["group_evoked_"+exp] =
mne.grand_average(locals()["evoked_"+exp], drop_bads=True)

Can someone pint out what was wrong with code? Thanks

Best,
Veda
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hi,

read_evokeds returns a list. If you want one evoked take the first element
or specify the condition you want to read.

A