[Python] How to Count Element Frequencies in a DolphinDB Array

I need to count the occurrences of each element in a DolphinDB array, similar to Python’s collections.Counter. In Python, this works:

from collections import Counter
my_list = [1, 2, 3, 2, 1, 3, 2, 1]
my_counter = Counter(my_list)
print(my_counter) # Output: Counter({1: 3, 2: 3, 3: 2})


In DolphinDB, I tried using groupby with count, but it failed:

myList = [1, 2, 3, 2, 1, 3, 2, 1]
groupby(count, myList, myList) // Error


Error: sage: groupby(func, funcArgs, groupingCol). func must be a function definition However, replacing count with avg works without errors:

groupby(avg, myList, myList) // Returns (1->1, 2->2, 3->3) but not frequency


Why does groupby fail with count but work with avg? Any solutions?

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