How to efficiently average same entries of lists in a list

[xquad]

The code shrinks down to:

indexlist = []
for t, scope_y in enumerate(scope_ys):
    scope_y = scope_y[0]
    indexes = peakutils.indexes(scope_y, thres=0.07, min_dist=500)
    indexlist.append(indexes)

df = pd.DataFrame.from_records(indexlist)
average = np.ones(4)
for i in range(len(indexes)):
    average[i] = int(np.average(df.iloc[:,i]))

Te data type is a np array and looks like this: [3141. 4989. 5499. 6714.] such that in a subsequent for loop

for i, laser in enumerate(average):

the error occurs:
"slice indices must be integers or None or have an __index__ method"