Hi Darth,

I took a look at your code and I see both of the errors that you are reporting. The first (when lines 102 and 103 are uncommented), is related to the fact that your universe appears to be empty in combination with the fact that you are using the history() function to try to get the history of a specific stock. It's important to note that the history() function gets the volume history (in your case) for all stocks in your universe. If you would then like to look at the history of one stock, you can access it by doing something like this:

history(30, '1d', 'volume')[stock]

The second problem you are encountering seems to be related to the context.sector_mappings data structure. In your for loop on line 126, it seems that you are trying to write sectors for specific sids back to the structure that contains the sector code -> sector name mapping. Python doesn't let you add to a data structure that it is looping through so this is why you are seeing an error. In order to help you solve this one, do you think you could describe to me what the intended purpose of this code bit is?

Hello Jamie,

Thank you for your very swift response!

I’ll go through my logic from start to finish just in case it gives you an idea for a workaround.

Def long_basket/def short_basket: the purpose of this function is to select ~20 stocks from all those available and group them based on fundamental criteria. One group has specific parameters that are desirable for a long position, the other for a short position. In this scenario, they are sorted by PE ratio accordingly.

Def long_filter/def short_filter: the purpose of this function is to take the 20 stocks from the long_basket and remove those that do not meet a minimum average volume scalable by account size, remove stocks that are scheduled to delist, remove the SPY etf, remove flagged stocks and remove leveraged ETFs.

Def long_trending/def short_trending: the purpose of this function is to take the remaining stocks from the long_trending, add the sector mappings so we know what sector it is in, and remove those that where their corresponding ETF is below the 200day moving average. For example if an energy stock is in the long_trending group but XLE is below it’s 200 day MA, then it would be removed. If a stock is in the short_trending group and its corresponding sector ETF is above it’s 200 day moving average, then it is removed from the group. Lastly, the groups are paired down to a max number of stocks based on the number of trending ETFs. For example in the compute_conditional_weights, if it is determined that 2 ETFs have a current daily price above their 200 DMA of the 9 ETFs in sector_mappingsetf then this corresponds with choosing 25% of the context.num_stocks (in this case 5) to go long with and 75% (in this case 15) stocks to go short with. The compute_conditional_weights settings can let me go as long or as short as I want once I find out the optimum balance.

Def rebalance: This section would long 5 stocks and short 15 stocks if context.num_stocks was = 20. Long 4 stocks and short 12 stocks if context.num_stocks was = 16, etc.

Def has_orders: This prevents ordering when orders are pending.

If you have any other questions, please don’t hesitate to ask. Thank you for taking a look at the algo.

I suggest you take a look at this example from the help docs. The example looks at sector codes from a fundamentals query as well as shows how to update your universe with stocks returned from the query. I think this should help you with the problems I mentioned in my previous post!

Hello Jamie,
Your link does not seem to point to any help docs.

My fault, I gave you a bad link, try again now!

Jamie,
Your first suggestion doesn't work. As per the API and help docs, that is the first place I go to when I get stuck. If I could have solved it using the help docs, I wouldn't have posted it in the forums. I guess it will have to remain unsolved. Thanks for your suggestions none the less.