Ejemplo n.º 1
0
        /// <summary>
        /// Applies universe selection the the data feed and algorithm
        /// </summary>
        /// <param name="universe">The universe to perform selection on</param>
        /// <param name="dateTimeUtc">The current date time in utc</param>
        /// <param name="universeData">The data provided to perform selection with</param>
        public SecurityChanges ApplyUniverseSelection(Universe universe, DateTime dateTimeUtc, BaseDataCollection universeData)
        {
            var settings = universe.UniverseSettings;

            // perform initial filtering and limit the result
            var selectSymbolsResult = universe.PerformSelection(dateTimeUtc, universeData);

            // check for no changes first
            if (ReferenceEquals(selectSymbolsResult, Universe.Unchanged))
            {
                return(SecurityChanges.None);
            }

            // materialize the enumerable into a set for processing
            var selections = selectSymbolsResult.ToHashSet();

            // create a hash set of our existing subscriptions by sid
            var existingSubscriptions = _dataFeed.Subscriptions.ToHashSet(x => x.Security.Symbol);

            var additions = new List <Security>();
            var removals  = new List <Security>();

            // determine which data subscriptions need to be removed from this universe
            foreach (var member in universe.Members.Values)
            {
                var config = member.SubscriptionDataConfig;

                // if we've selected this subscription again, keep it
                if (selections.Contains(config.Symbol))
                {
                    continue;
                }

                // don't remove if the universe wants to keep him in
                if (!universe.CanRemoveMember(dateTimeUtc, member))
                {
                    continue;
                }

                // remove the member - this marks this member as not being
                // selected by the universe, but it may remain in the universe
                // until open orders are closed and the security is liquidated
                removals.Add(member);

                // but don't physically remove it from the algorithm if we hold stock or have open orders against it
                var openOrders = _algorithm.Transactions.GetOrders(x => x.Status.IsOpen() && x.Symbol == config.Symbol);
                if (!member.HoldStock && !openOrders.Any())
                {
                    // safe to remove the member from the universe
                    universe.RemoveMember(dateTimeUtc, member);

                    // we need to mark this security as untradeable while it has no data subscription
                    // it is expected that this function is called while in sync with the algo thread,
                    // so we can make direct edits to the security here
                    member.Cache.Reset();
                    _dataFeed.RemoveSubscription(member.Symbol);
                }
            }

            // find new selections and add them to the algorithm
            foreach (var symbol in selections)
            {
                // we already have a subscription for this symbol so don't re-add it
                if (existingSubscriptions.Contains(symbol))
                {
                    continue;
                }

                // create the new security, the algorithm thread will add this at the appropriate time
                Security security;
                if (!_algorithm.Securities.TryGetValue(symbol, out security))
                {
                    security = universe.CreateSecurity(symbol, _algorithm, _marketHoursDatabase, _symbolPropertiesDatabase);
                }

                additions.Add(security);

                var addedSubscription = false;
                foreach (var config in universe.GetSubscriptions(security))
                {
                    // ask the limiter if we can add another subscription at that resolution
                    string reason;
                    if (!_limiter.CanAddSubscription(config.Resolution, out reason))
                    {
                        _algorithm.Error(reason);
                        Log.Trace("UniverseSelection.ApplyUniverseSelection(): Skipping adding subscription: " + config.Symbol.ToString() + ": " + reason);
                        continue;
                    }

                    // add the new subscriptions to the data feed
                    if (_dataFeed.AddSubscription(universe, security, config, dateTimeUtc, _algorithm.EndDate.ConvertToUtc(_algorithm.TimeZone)))
                    {
                        addedSubscription = true;
                    }
                }

                if (addedSubscription)
                {
                    universe.AddMember(dateTimeUtc, security);
                }
            }

            // Add currency data feeds that weren't explicitly added in Initialize
            if (additions.Count > 0)
            {
                var addedSecurities = _algorithm.Portfolio.CashBook.EnsureCurrencyDataFeeds(_algorithm.Securities, _algorithm.SubscriptionManager, _marketHoursDatabase, _symbolPropertiesDatabase, _algorithm.BrokerageModel.DefaultMarkets);
                foreach (var security in addedSecurities)
                {
                    // assume currency feeds are always one subscription per, these are typically quote subscriptions
                    _dataFeed.AddSubscription(universe, security, security.SubscriptionDataConfig, dateTimeUtc, _algorithm.EndDate.ConvertToUtc(_algorithm.TimeZone));
                }
            }

            // return None if there's no changes, otherwise return what we've modified
            return(additions.Count + removals.Count != 0
                ? new SecurityChanges(additions, removals)
                : SecurityChanges.None);
        }
Ejemplo n.º 2
0
        /// <summary>
        /// Applies universe selection the the data feed and algorithm
        /// </summary>
        /// <param name="universe">The universe to perform selection on</param>
        /// <param name="dateTimeUtc">The current date time in utc</param>
        /// <param name="universeData">The data provided to perform selection with</param>
        public SecurityChanges ApplyUniverseSelection(Universe universe, DateTime dateTimeUtc, BaseDataCollection universeData)
        {
            var algorithmEndDateUtc = _algorithm.EndDate.ConvertToUtc(_algorithm.TimeZone);

            if (dateTimeUtc > algorithmEndDateUtc)
            {
                return(SecurityChanges.None);
            }

            IEnumerable <Symbol> selectSymbolsResult;

            // check if this universe must be filtered with fine fundamental data
            var fineFiltered = universe as FineFundamentalFilteredUniverse;

            if (fineFiltered != null)
            {
                // perform initial filtering and limit the result
                selectSymbolsResult = universe.SelectSymbols(dateTimeUtc, universeData);

                if (!ReferenceEquals(selectSymbolsResult, Universe.Unchanged))
                {
                    // prepare a BaseDataCollection of FineFundamental instances
                    var fineCollection = new BaseDataCollection();
                    var dataProvider   = new DefaultDataProvider();

                    foreach (var symbol in selectSymbolsResult)
                    {
                        var config = FineFundamentalUniverse.CreateConfiguration(symbol);

                        var exchangeHours    = _marketHoursDatabase.GetEntry(symbol.ID.Market, symbol, symbol.ID.SecurityType).ExchangeHours;
                        var symbolProperties = _symbolPropertiesDatabase.GetSymbolProperties(symbol.ID.Market, symbol, symbol.ID.SecurityType, CashBook.AccountCurrency);
                        var quoteCash        = _algorithm.Portfolio.CashBook[symbolProperties.QuoteCurrency];

                        var security = new Equity(symbol, exchangeHours, quoteCash, symbolProperties);

                        var localStartTime = dateTimeUtc.ConvertFromUtc(exchangeHours.TimeZone).AddDays(-1);
                        var factory        = new FineFundamentalSubscriptionEnumeratorFactory(_algorithm.LiveMode, x => new[] { localStartTime });
                        var request        = new SubscriptionRequest(true, universe, security, new SubscriptionDataConfig(config), localStartTime, localStartTime);
                        using (var enumerator = factory.CreateEnumerator(request, dataProvider))
                        {
                            if (enumerator.MoveNext())
                            {
                                fineCollection.Data.Add(enumerator.Current);
                            }
                        }
                    }

                    // perform the fine fundamental universe selection
                    selectSymbolsResult = fineFiltered.FineFundamentalUniverse.PerformSelection(dateTimeUtc, fineCollection);

                    // WARNING -- HACK ATTACK -- WARNING
                    // Fine universes are considered special due to their chaining behavior.
                    // As such, we need a means of piping the fine data read in here back to the data feed
                    // so that it can be properly emitted via a TimeSlice.Create call. There isn't a mechanism
                    // in place for this function to return such data. The following lines are tightly coupled
                    // to the universeData dictionaries in SubscriptionSynchronizer and LiveTradingDataFeed and
                    // rely on reference semantics to work.

                    // Coarse raw data has SID collision on: CRHCY R735QTJ8XC9X
                    var coarseData = universeData.Data.OfType <CoarseFundamental>()
                                     .DistinctBy(c => c.Symbol)
                                     .ToDictionary(c => c.Symbol);

                    universeData.Data = new List <BaseData>();
                    foreach (var fine in fineCollection.Data.OfType <FineFundamental>())
                    {
                        var fundamentals = new Fundamentals
                        {
                            Symbol              = fine.Symbol,
                            Time                = fine.Time,
                            EndTime             = fine.EndTime,
                            DataType            = fine.DataType,
                            CompanyReference    = fine.CompanyReference,
                            EarningReports      = fine.EarningReports,
                            EarningRatios       = fine.EarningRatios,
                            FinancialStatements = fine.FinancialStatements,
                            OperationRatios     = fine.OperationRatios,
                            SecurityReference   = fine.SecurityReference,
                            ValuationRatios     = fine.ValuationRatios
                        };

                        CoarseFundamental coarse;
                        if (coarseData.TryGetValue(fine.Symbol, out coarse))
                        {
                            // the only time the coarse data won't exist is if the selection function
                            // doesn't use the data provided, and instead returns a constant list of
                            // symbols -- coupled with a potential hole in the data
                            fundamentals.Value              = coarse.Value;
                            fundamentals.Market             = coarse.Market;
                            fundamentals.Volume             = coarse.Volume;
                            fundamentals.DollarVolume       = coarse.DollarVolume;
                            fundamentals.HasFundamentalData = coarse.HasFundamentalData;
                        }

                        universeData.Data.Add(fundamentals);
                    }

                    // END -- HACK ATTACK -- END
                }
            }
            else
            {
                // perform initial filtering and limit the result
                selectSymbolsResult = universe.PerformSelection(dateTimeUtc, universeData);
            }

            // check for no changes first
            if (ReferenceEquals(selectSymbolsResult, Universe.Unchanged))
            {
                return(SecurityChanges.None);
            }

            // materialize the enumerable into a set for processing
            var selections = selectSymbolsResult.ToHashSet();

            var additions = new List <Security>();
            var removals  = new List <Security>();

            // remove previously deselected members which were kept in the universe because of holdings or open orders
            foreach (var member in _pendingRemovals.ToList())
            {
                if (IsSafeToRemove(member))
                {
                    RemoveSecurityFromUniverse(universe, member, removals, dateTimeUtc, algorithmEndDateUtc);

                    _pendingRemovals.Remove(member);
                }
            }

            // determine which data subscriptions need to be removed from this universe
            foreach (var member in universe.Members.Values)
            {
                // if we've selected this subscription again, keep it
                if (selections.Contains(member.Symbol))
                {
                    continue;
                }

                // don't remove if the universe wants to keep him in
                if (!universe.CanRemoveMember(dateTimeUtc, member))
                {
                    continue;
                }

                // remove the member - this marks this member as not being
                // selected by the universe, but it may remain in the universe
                // until open orders are closed and the security is liquidated
                removals.Add(member);

                if (IsSafeToRemove(member))
                {
                    RemoveSecurityFromUniverse(universe, member, removals, dateTimeUtc, algorithmEndDateUtc);
                }
                else
                {
                    _pendingRemovals.Add(member);
                }
            }

            var keys = _pendingSecurityAdditions.Keys;

            if (keys.Any() && keys.Single() != dateTimeUtc)
            {
                // if the frontier moved forward then we've added these securities to the algorithm
                _pendingSecurityAdditions.Clear();
            }

            Dictionary <Symbol, Security> pendingAdditions;

            if (!_pendingSecurityAdditions.TryGetValue(dateTimeUtc, out pendingAdditions))
            {
                // keep track of created securities so we don't create the same security twice, leads to bad things :)
                pendingAdditions = new Dictionary <Symbol, Security>();
                _pendingSecurityAdditions[dateTimeUtc] = pendingAdditions;
            }

            // find new selections and add them to the algorithm
            foreach (var symbol in selections)
            {
                // create the new security, the algorithm thread will add this at the appropriate time
                Security security;
                if (!pendingAdditions.TryGetValue(symbol, out security) && !_algorithm.Securities.TryGetValue(symbol, out security))
                {
                    security = universe.CreateSecurity(symbol, _algorithm, _marketHoursDatabase, _symbolPropertiesDatabase);
                    pendingAdditions.Add(symbol, security);
                }

                var addedSubscription = false;

                foreach (var request in universe.GetSubscriptionRequests(security, dateTimeUtc, algorithmEndDateUtc))
                {
                    // add the new subscriptions to the data feed
                    _dataFeed.AddSubscription(request);

                    // only update our security changes if we actually added data
                    if (!request.IsUniverseSubscription)
                    {
                        addedSubscription = true;
                    }
                }

                if (addedSubscription)
                {
                    var addedMember = universe.AddMember(dateTimeUtc, security);

                    if (addedMember)
                    {
                        additions.Add(security);
                    }
                }
            }

            // return None if there's no changes, otherwise return what we've modified
            var securityChanges = additions.Count + removals.Count != 0
                ? new SecurityChanges(additions, removals)
                : SecurityChanges.None;

            // Add currency data feeds that weren't explicitly added in Initialize
            if (additions.Count > 0)
            {
                var addedSecurities = _algorithm.Portfolio.CashBook.EnsureCurrencyDataFeeds(_algorithm.Securities, _algorithm.SubscriptionManager, _marketHoursDatabase, _symbolPropertiesDatabase, _algorithm.BrokerageModel.DefaultMarkets, securityChanges);
                foreach (var security in addedSecurities)
                {
                    // assume currency feeds are always one subscription per, these are typically quote subscriptions
                    _dataFeed.AddSubscription(new SubscriptionRequest(false, universe, security, new SubscriptionDataConfig(security.Subscriptions.First()), dateTimeUtc, algorithmEndDateUtc));
                }
            }

            if (securityChanges != SecurityChanges.None)
            {
                Log.Debug("UniverseSelection.ApplyUniverseSelection(): " + dateTimeUtc + ": " + securityChanges);
            }

            return(securityChanges);
        }
        /// <summary>
        /// Applies universe selection the the data feed and algorithm
        /// </summary>
        /// <param name="universe">The universe to perform selection on</param>
        /// <param name="dateTimeUtc">The current date time in utc</param>
        /// <param name="universeData">The data provided to perform selection with</param>
        public SecurityChanges ApplyUniverseSelection(Universe universe, DateTime dateTimeUtc, BaseDataCollection universeData)
        {
            IEnumerable <Symbol> selectSymbolsResult;

            // check if this universe must be filtered with fine fundamental data
            var fineFiltered = universe as FineFundamentalFilteredUniverse;

            if (fineFiltered != null)
            {
                // perform initial filtering and limit the result
                selectSymbolsResult = universe.SelectSymbols(dateTimeUtc, universeData);

                // prepare a BaseDataCollection of FineFundamental instances
                var fineCollection = new BaseDataCollection();
                var dataProvider   = new DefaultDataProvider();

                foreach (var symbol in selectSymbolsResult)
                {
                    var factory = new FineFundamentalSubscriptionEnumeratorFactory(_algorithm.LiveMode, x => new[] { dateTimeUtc });
                    var config  = FineFundamentalUniverse.CreateConfiguration(symbol);

                    Security security;
                    if (!_algorithm.Securities.TryGetValue(symbol, out security))
                    {
                        security = universe.CreateSecurity(symbol, _algorithm, _marketHoursDatabase, _symbolPropertiesDatabase);
                        _algorithm.Securities.Add(security);
                    }

                    var request    = new SubscriptionRequest(true, universe, security, config, dateTimeUtc, dateTimeUtc);
                    var enumerator = factory.CreateEnumerator(request, dataProvider);
                    if (enumerator.MoveNext())
                    {
                        fineCollection.Data.Add(enumerator.Current);
                    }
                }

                // perform the fine fundamental universe selection
                selectSymbolsResult = fineFiltered.FineFundamentalUniverse.PerformSelection(dateTimeUtc, fineCollection);
            }
            else
            {
                // perform initial filtering and limit the result
                selectSymbolsResult = universe.PerformSelection(dateTimeUtc, universeData);
            }

            // check for no changes first
            if (ReferenceEquals(selectSymbolsResult, Universe.Unchanged))
            {
                return(SecurityChanges.None);
            }

            // materialize the enumerable into a set for processing
            var selections = selectSymbolsResult.ToHashSet();

            var additions           = new List <Security>();
            var removals            = new List <Security>();
            var algorithmEndDateUtc = _algorithm.EndDate.ConvertToUtc(_algorithm.TimeZone);

            // remove previously deselected members which were kept in the universe because of holdings or open orders
            foreach (var member in _pendingRemovals.ToList())
            {
                var openOrders = _algorithm.Transactions.GetOrders(x => x.Status.IsOpen() && x.Symbol == member.Symbol);
                if (!member.HoldStock && !openOrders.Any())
                {
                    RemoveSecurityFromUniverse(universe, member, removals, dateTimeUtc, algorithmEndDateUtc);

                    _pendingRemovals.Remove(member);
                }
            }

            // determine which data subscriptions need to be removed from this universe
            foreach (var member in universe.Members.Values)
            {
                // if we've selected this subscription again, keep it
                if (selections.Contains(member.Symbol))
                {
                    continue;
                }

                // don't remove if the universe wants to keep him in
                if (!universe.CanRemoveMember(dateTimeUtc, member))
                {
                    continue;
                }

                // remove the member - this marks this member as not being
                // selected by the universe, but it may remain in the universe
                // until open orders are closed and the security is liquidated
                removals.Add(member);

                // but don't physically remove it from the algorithm if we hold stock or have open orders against it
                var openOrders = _algorithm.Transactions.GetOrders(x => x.Status.IsOpen() && x.Symbol == member.Symbol);
                if (!member.HoldStock && !openOrders.Any())
                {
                    RemoveSecurityFromUniverse(universe, member, removals, dateTimeUtc, algorithmEndDateUtc);
                }
                else
                {
                    _pendingRemovals.Add(member);
                }
            }

            // find new selections and add them to the algorithm
            foreach (var symbol in selections)
            {
                // create the new security, the algorithm thread will add this at the appropriate time
                Security security;
                if (!_algorithm.Securities.TryGetValue(symbol, out security))
                {
                    security = universe.CreateSecurity(symbol, _algorithm, _marketHoursDatabase, _symbolPropertiesDatabase);
                }

                var addedSubscription = false;

                foreach (var request in universe.GetSubscriptionRequests(security, dateTimeUtc, algorithmEndDateUtc))
                {
                    // ask the limiter if we can add another subscription at that resolution
                    string reason;
                    if (!_limiter.CanAddSubscription(request.Configuration.Resolution, out reason))
                    {
                        // should we be counting universe subscriptions against user subscriptions limits?

                        _algorithm.Error(reason);
                        Log.Trace("UniverseSelection.ApplyUniverseSelection(): Skipping adding subscription: " + request.Configuration.Symbol.ToString() + ": " + reason);
                        continue;
                    }
                    // add the new subscriptions to the data feed
                    _dataFeed.AddSubscription(request);

                    // only update our security changes if we actually added data
                    if (!request.IsUniverseSubscription)
                    {
                        addedSubscription = true;
                    }
                }

                if (addedSubscription)
                {
                    var addedMember = universe.AddMember(dateTimeUtc, security);

                    if (addedMember)
                    {
                        additions.Add(security);
                    }
                }
            }

            // Add currency data feeds that weren't explicitly added in Initialize
            if (additions.Count > 0)
            {
                var addedSecurities = _algorithm.Portfolio.CashBook.EnsureCurrencyDataFeeds(_algorithm.Securities, _algorithm.SubscriptionManager, _marketHoursDatabase, _symbolPropertiesDatabase, _algorithm.BrokerageModel.DefaultMarkets);
                foreach (var security in addedSecurities)
                {
                    // assume currency feeds are always one subscription per, these are typically quote subscriptions
                    _dataFeed.AddSubscription(new SubscriptionRequest(false, universe, security, security.Subscriptions.First(), dateTimeUtc, algorithmEndDateUtc));
                }
            }

            // return None if there's no changes, otherwise return what we've modified
            var securityChanges = additions.Count + removals.Count != 0
                ? new SecurityChanges(additions, removals)
                : SecurityChanges.None;

            if (securityChanges != SecurityChanges.None)
            {
                Log.Debug("UniverseSelection.ApplyUniverseSelection(): " + dateTimeUtc + ": " + securityChanges);
            }

            return(securityChanges);
        }
Ejemplo n.º 4
0
        /// <summary>
        /// Applies universe selection the the data feed and algorithm
        /// </summary>
        /// <param name="universe">The universe to perform selection on</param>
        /// <param name="dateTimeUtc">The current date time in utc</param>
        /// <param name="universeData">The data provided to perform selection with</param>
        public SecurityChanges ApplyUniverseSelection(Universe universe, DateTime dateTimeUtc, BaseDataCollection universeData)
        {
            var algorithmEndDateUtc = _algorithm.EndDate.ConvertToUtc(_algorithm.TimeZone);

            if (dateTimeUtc > algorithmEndDateUtc)
            {
                return(SecurityChanges.None);
            }

            IEnumerable <Symbol> selectSymbolsResult;

            // check if this universe must be filtered with fine fundamental data
            var fineFiltered = universe as FineFundamentalFilteredUniverse;

            if (fineFiltered != null)
            {
                // perform initial filtering and limit the result
                selectSymbolsResult = universe.SelectSymbols(dateTimeUtc, universeData);

                if (!ReferenceEquals(selectSymbolsResult, Universe.Unchanged))
                {
                    // prepare a BaseDataCollection of FineFundamental instances
                    var fineCollection = new BaseDataCollection();
                    var dataProvider   = new DefaultDataProvider();

                    foreach (var symbol in selectSymbolsResult)
                    {
                        var factory = new FineFundamentalSubscriptionEnumeratorFactory(_algorithm.LiveMode, x => new[] { dateTimeUtc });
                        var config  = FineFundamentalUniverse.CreateConfiguration(symbol);

                        var exchangeHours    = _marketHoursDatabase.GetEntry(symbol.ID.Market, symbol, symbol.ID.SecurityType).ExchangeHours;
                        var symbolProperties = _symbolPropertiesDatabase.GetSymbolProperties(symbol.ID.Market, symbol, symbol.ID.SecurityType, CashBook.AccountCurrency);
                        var quoteCash        = _algorithm.Portfolio.CashBook[symbolProperties.QuoteCurrency];

                        var security = new Equity(symbol, exchangeHours, quoteCash, symbolProperties);

                        var request = new SubscriptionRequest(true, universe, security, new SubscriptionDataConfig(config), dateTimeUtc, dateTimeUtc);
                        using (var enumerator = factory.CreateEnumerator(request, dataProvider))
                        {
                            if (enumerator.MoveNext())
                            {
                                fineCollection.Data.Add(enumerator.Current);
                            }
                        }
                    }

                    // perform the fine fundamental universe selection
                    selectSymbolsResult = fineFiltered.FineFundamentalUniverse.PerformSelection(dateTimeUtc, fineCollection);
                }
            }
            else
            {
                // perform initial filtering and limit the result
                selectSymbolsResult = universe.PerformSelection(dateTimeUtc, universeData);
            }

            // check for no changes first
            if (ReferenceEquals(selectSymbolsResult, Universe.Unchanged))
            {
                return(SecurityChanges.None);
            }

            // materialize the enumerable into a set for processing
            var selections = selectSymbolsResult.ToHashSet();

            var additions = new List <Security>();
            var removals  = new List <Security>();

            // remove previously deselected members which were kept in the universe because of holdings or open orders
            foreach (var member in _pendingRemovals.ToList())
            {
                if (IsSafeToRemove(member))
                {
                    RemoveSecurityFromUniverse(universe, member, removals, dateTimeUtc, algorithmEndDateUtc);

                    _pendingRemovals.Remove(member);
                }
            }

            // determine which data subscriptions need to be removed from this universe
            foreach (var member in universe.Members.Values)
            {
                // if we've selected this subscription again, keep it
                if (selections.Contains(member.Symbol))
                {
                    continue;
                }

                // don't remove if the universe wants to keep him in
                if (!universe.CanRemoveMember(dateTimeUtc, member))
                {
                    continue;
                }

                // remove the member - this marks this member as not being
                // selected by the universe, but it may remain in the universe
                // until open orders are closed and the security is liquidated
                removals.Add(member);

                if (IsSafeToRemove(member))
                {
                    RemoveSecurityFromUniverse(universe, member, removals, dateTimeUtc, algorithmEndDateUtc);
                }
                else
                {
                    _pendingRemovals.Add(member);
                }
            }

            var keys = _pendingSecurityAdditions.Keys;

            if (keys.Any() && keys.Single() != dateTimeUtc)
            {
                // if the frontier moved forward then we've added these securities to the algorithm
                _pendingSecurityAdditions.Clear();
            }

            Dictionary <Symbol, Security> pendingAdditions;

            if (!_pendingSecurityAdditions.TryGetValue(dateTimeUtc, out pendingAdditions))
            {
                // keep track of created securities so we don't create the same security twice, leads to bad things :)
                pendingAdditions = new Dictionary <Symbol, Security>();
                _pendingSecurityAdditions[dateTimeUtc] = pendingAdditions;
            }

            // find new selections and add them to the algorithm
            foreach (var symbol in selections)
            {
                // create the new security, the algorithm thread will add this at the appropriate time
                Security security;
                if (!pendingAdditions.TryGetValue(symbol, out security) && !_algorithm.Securities.TryGetValue(symbol, out security))
                {
                    security = universe.CreateSecurity(symbol, _algorithm, _marketHoursDatabase, _symbolPropertiesDatabase);
                    pendingAdditions.Add(symbol, security);
                }

                var addedSubscription = false;

                foreach (var request in universe.GetSubscriptionRequests(security, dateTimeUtc, algorithmEndDateUtc))
                {
                    // add the new subscriptions to the data feed
                    _dataFeed.AddSubscription(request);

                    // only update our security changes if we actually added data
                    if (!request.IsUniverseSubscription)
                    {
                        addedSubscription = true;
                    }
                }

                if (addedSubscription)
                {
                    var addedMember = universe.AddMember(dateTimeUtc, security);

                    if (addedMember)
                    {
                        additions.Add(security);
                    }
                }
            }

            // return None if there's no changes, otherwise return what we've modified
            var securityChanges = additions.Count + removals.Count != 0
                ? new SecurityChanges(additions, removals)
                : SecurityChanges.None;

            // Add currency data feeds that weren't explicitly added in Initialize
            if (additions.Count > 0)
            {
                var addedSecurities = _algorithm.Portfolio.CashBook.EnsureCurrencyDataFeeds(_algorithm.Securities, _algorithm.SubscriptionManager, _marketHoursDatabase, _symbolPropertiesDatabase, _algorithm.BrokerageModel.DefaultMarkets, securityChanges);
                foreach (var security in addedSecurities)
                {
                    // assume currency feeds are always one subscription per, these are typically quote subscriptions
                    _dataFeed.AddSubscription(new SubscriptionRequest(false, universe, security, new SubscriptionDataConfig(security.Subscriptions.First()), dateTimeUtc, algorithmEndDateUtc));
                }
            }

            if (securityChanges != SecurityChanges.None)
            {
                Log.Debug("UniverseSelection.ApplyUniverseSelection(): " + dateTimeUtc + ": " + securityChanges);
            }

            return(securityChanges);
        }