Would love help with a long/short strategy

I've done multiple changes to this algorithm in order to fix it but the error code still occurs.

from System.Collections.Generic import List
from QuantConnect.Data.UniverseSelection import *

class BasicTemplateAlgorithm(QCAlgorithm):

def __init__(self):
# set the flag for rebalance
self.reb = 1
# Number of stocks to pass CoarseSelection process
self.num_coarse = 250
# Number of stocks to long/short
self.num_fine = 20
self.symbols = None
self.first_month = 0

def Initialize(self):
# if not specified, the Backtesting EndDate would be today
# self.SetEndDate(2017,1,1)

self.spy = self.AddEquity("SPY", Resolution.Daily).Symbol

self.UniverseSettings.Resolution = Resolution.Daily


# Schedule the rebalance function to execute at the begining of each month
self.TimeRules.AfterMarketOpen(self.spy,5), Action(self.rebalance))

def CoarseSelectionFunction(self, coarse):
# if the rebalance flag is not 1, return null list to save time.
if self.reb != 1:
return (List[Symbol]())

# make universe selection once a month
# drop stocks which have no fundamental data or have too low prices
selected = [x for x in coarse if (x.HasFundamentalData)
and (float(x.Price) > 5)]

sortedByDollarVolume = sorted(selected, key=lambda x: x.DollarVolume, reverse=True)
top = sortedByDollarVolume[:self.num_coarse]
list = List[Symbol]()
for x in top:
return list

def FineSelectionFunction(self, fine):
# return null list if it's not time to rebalance
if self.reb != 1:
return (List[Symbol]())

self.reb = 0

# drop stocks which don't have the information we need.
# you can try replacing those factor with your own factors here

filtered_fine = [x for x in fine if x.OperationRatios.OperationMargin.Value
and x.ValuationRatios.PriceChange1M
and x.ValuationRatios.BookValuePerShare]

self.Log('remained to select %d'%(len(filtered_fine)))

# rank stocks by three factor.
sortedByfactor1 = sorted(filtered_fine, key=lambda x: x.OperationRatios.OperationMargin.Value, reverse=True)
sortedByfactor2 = sorted(filtered_fine, key=lambda x: x.ValuationRatios.PriceChange1M, reverse=True)
sortedByfactor3 = sorted(filtered_fine, key=lambda x: x.ValuationRatios.BookValuePerShare, reverse=True)

stock_dict = {}

# assign a score to each stock, you can also change the rule of scoring here.
for i,ele in enumerate(sortedByfactor1):
rank1 = i
rank2 = sortedByfactor2.index(ele)
rank3 = sortedByfactor3.index(ele)
score = sum([rank1*0.2,rank2*0.4,rank3*0.4])
stock_dict[ele] = score

# sort the stocks by their scores
self.sorted_stock = sorted(stock_dict.items(), key=lambda d:d[1],reverse=False)
sorted_symbol = [x[0] for x in self.sorted_stock]

# sotre the top stocks into the long_list and the bottom ones into the short_list
self.long = [x.Symbol for x in sorted_symbol[:self.num_fine]]
self.short = [x.Symbol for x in sorted_symbol[-self.num_fine:]]

topFine = self.long+self.short

list = List[Symbol]()
for x in topFine:

return list

def OnData(self, data):

def rebalance(self):
if self.first_month == 0:
self.first_month += 1
# if this month the stock are not going to be long/short, liquidate it.
long_short_list = self.long + self.short
for i in self.Portfolio.Values:
if (i.Invested) and (i.Symbol not in long_short_list):

# Alternatively, you can liquidate all the stocks at the end of each month.
# Which method to choose depends on your investment philosiphy
# if you prefer to realized the gain/loss each month, you can choose this method.


# Assign each stock equally. Alternatively you can design your own portfolio construction method
for i in self.long:

for i in self.short:

self.reb = 1
Update Backtest

It seems to be complaining about some conversion to a Python type to a System.Object[] in CoarseSelectionFunction. I can't really see why that is immediately, but have you tried commenting out code line by line until you find the line that's causing the issue?

Also, be aware the source algo you're building on was found to be problematic because it's returning an empty list when rebalance flag isn't set, leading to a serious bug (prices not being updated) because of securities being removed from universe intermittently.


The code that is an error is: 


According to the error code; "CoarseSelectionFunction" is not recognized by "BasicTemplateAlgorithm"


It looks like you are returning a C# List of symbols in 'CoarseSelectionFunction' and 'FineSelectionFunction'. This recently was changed so these functions now need a python list to be returned. (This unfortunately broke existing algorithms). Take a look at this post:

Change your code as suggested in the post. Should fix it. Good luck.


Update Backtest


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