Struggling with Select Override error when using FundamentalUniverseSelectionModel

Here's a corrected version of your CustomUniverseSelection class that resolves the runtime error and follows QuantConnect's framework conventions:

from AlgorithmImports import *

class CustomUniverseSelection(FundamentalUniverseSelectionModel):
    # Constructor now only uses valid universe_settings parameter, with universe_count as custom arg
    def __init__(self, universe_count: int = 10, universe_settings: UniverseSettings = None):
        super().__init__(universe_settings)
        self._universe_count: int = universe_count
        self._selection_data_by_symbol: dict[Symbol, CustomUniverseSelection.SelectionData] = {}

    # Properly overridden 'select' method—must be all lowercase
    def select(self, algorithm: QCAlgorithm, fundamentals: list[Fundamental]) -> list[Symbol]:
        for f in fundamentals:
            symbol = f.symbol
            price = f.adjusted_price
            volume = f.dollar_volume
            end_time = f.end_time

            if symbol not in self._selection_data_by_symbol:
                self._selection_data_by_symbol[symbol] = self.SelectionData(algorithm, symbol, 200)
            self._selection_data_by_symbol[symbol].update(end_time, price, volume)

        # Select stocks above their EMA and with a daily dollar volume over $1B
        selected = [x for x in self._selection_data_by_symbol.values() if x.is_above_ema and x.volume > 1_000_000_000]
        # Return the most liquid according to your universe count
        selected = sorted(selected, key=lambda x: x.volume)[-self._universe_count:]
        return [x.symbol for x in selected]

    class SelectionData:
        def __init__(self, algorithm: QCAlgorithm, symbol: Symbol, period: int):
            self.symbol: Symbol = symbol
            self._ema = ExponentialMovingAverage(period)
            self.is_above_ema = False
            self.volume = 0.0
            algorithm.warm_up_indicator(symbol, self._ema, Resolution.DAILY)
        def update(self, time: datetime, price: float, volume: float) -> None:
            self.volume = volume
            if self._ema.update(time, price):
                self.is_above_ema = price > self._ema.current.value

# Example QCAlgorithm setup:
class UniverseSelectionAlgorithm(QCAlgorithm):
    def initialize(self):
        self.set_start_date(2021, 1, 1)
        self.set_end_date(2022, 1, 1)
        self.set_cash(100000)
        # Correct way: add the custom universe selection model
        self.add_universe_selection(CustomUniverseSelection(universe_count=10))

Key Fixes:

• The method must be named select (not Select).
• The parent class's constructor must not be passed invalid args (just use universe_settings or nothing).
• The structure is properly nested and correctly indented for Python.
• Minimal QCAlgorithm example ensures valid usage.

This code should eliminate your runtime error and provide a working foundation for your fundamental universe selection. Let me know if you need further help!

Sources: docs writing algorithms datasets morningstar us fundamental data, Custom Universe Selection Model Regression Algorithm, Fundamental Universe Selection Algorithm, Fundamental Universes - QuantConnect.com, Fundamental Universe Selection Regression Algorithm

it doesn't work. I still got below error. 

Runtime Error: If inheriting, please overrride the 'Select' fundamental function, else provide it as a constructor parameter in FundamentalUniverseSelectionModel.cs:line 203 (Open Stack Trace)

I ran into this too…super frustrating.

I think it was a missing import:

`from Selection.FundamentalUniverseSelectionModel import FundamentalUniverseSelectionModel `