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Did you find a bug? Sorry about that! Please tell us about it here.

We launched our alpha version of the software. All software has bugs, and alpha software . . . yeah, we're going to find bugs! We thank you all for your interest, and we apologize for any errors you find.

The more detail you can give us, the better. Let us know what you were doing, how we can reproduce the problem, what you saw, and what you actually expected to see.

Thank you!

Disclaimer

The material on this website is provided for informational purposes only and does not constitute an offer to sell, a solicitation to buy, or a recommendation or endorsement for any security or strategy, nor does it constitute an offer to provide investment advisory services by Quantopian. In addition, the material offers no opinion with respect to the suitability of any security or specific investment. No information contained herein should be regarded as a suggestion to engage in or refrain from any investment-related course of action as none of Quantopian nor any of its affiliates is undertaking to provide investment advice, act as an adviser to any plan or entity subject to the Employee Retirement Income Security Act of 1974, as amended, individual retirement account or individual retirement annuity, or give advice in a fiduciary capacity with respect to the materials presented herein. If you are an individual retirement or other investor, contact your financial advisor or other fiduciary unrelated to Quantopian about whether any given investment idea, strategy, product or service described herein may be appropriate for your circumstances. All investments involve risk, including loss of principal. Quantopian makes no guarantees as to the accuracy or completeness of the views expressed in the website. The views are subject to change, and may have become unreliable for various reasons, including changes in market conditions or economic circumstances.

23 responses

I cloned the AAPL backtest demo, and changed the initial capital amount down to 10,000 and ran the test. The backtester said "canceled" immediately. Now when I try to view the results from the backtest, it never loads.

Rob, thanks for the heads up. We are looking into the issue.

Disclaimer

The material on this website is provided for informational purposes only and does not constitute an offer to sell, a solicitation to buy, or a recommendation or endorsement for any security or strategy, nor does it constitute an offer to provide investment advisory services by Quantopian. In addition, the material offers no opinion with respect to the suitability of any security or specific investment. No information contained herein should be regarded as a suggestion to engage in or refrain from any investment-related course of action as none of Quantopian nor any of its affiliates is undertaking to provide investment advice, act as an adviser to any plan or entity subject to the Employee Retirement Income Security Act of 1974, as amended, individual retirement account or individual retirement annuity, or give advice in a fiduciary capacity with respect to the materials presented herein. If you are an individual retirement or other investor, contact your financial advisor or other fiduciary unrelated to Quantopian about whether any given investment idea, strategy, product or service described herein may be appropriate for your circumstances. All investments involve risk, including loss of principal. Quantopian makes no guarantees as to the accuracy or completeness of the views expressed in the website. The views are subject to change, and may have become unreliable for various reasons, including changes in market conditions or economic circumstances.

here's a couple quick bugs. Is this the best place for them?

  • I had one backtest run that successfully completed, but the UI rendered the backtest as a bit frozen on the front end, stuck at 70%-ish. Once went to all my backtests and came back into the test again, I could see that it completed.
  • In the forums, I'm not sure how to make white spacing work correctly with the code snippet feature. I'm in chrome on a mac. I'm having trouble making the code snippet feature capture both newlines and tabs.
  • also in the forums, if I type an underscored function name such as "I_am_a_underscored_function" the underscores are lost and converted to italics upon posting.

Hello Andrew - Can you drop me an email with the name or URL of the backtest that you had hte problem with?

On the forums, we have corrected a few bugs with the way code and blockquotes render, but I won't be shocked when we find some new ones! Can you send me that sample too so I can look into it?

For italics, it currently supports both * and . star and _under give the same result. Your point on the function names is a good one. We'll take out the underscore so it's only the *.

+1 for fixing the underscore to italics conversion.

Hi, I have a "Loading..." without ending when loading every algorithm share in community problem in Google Chrome. Seems a bug?

Hi Raymond,

Thanks for the problem report.

I seem to be able to run backtests, so I'm not sure what problem you're having. Can you be more specific about exactly what steps you are taking so I can try harder to reproduce the issue?

Thanks.

Disclaimer

The material on this website is provided for informational purposes only and does not constitute an offer to sell, a solicitation to buy, or a recommendation or endorsement for any security or strategy, nor does it constitute an offer to provide investment advisory services by Quantopian. In addition, the material offers no opinion with respect to the suitability of any security or specific investment. No information contained herein should be regarded as a suggestion to engage in or refrain from any investment-related course of action as none of Quantopian nor any of its affiliates is undertaking to provide investment advice, act as an adviser to any plan or entity subject to the Employee Retirement Income Security Act of 1974, as amended, individual retirement account or individual retirement annuity, or give advice in a fiduciary capacity with respect to the materials presented herein. If you are an individual retirement or other investor, contact your financial advisor or other fiduciary unrelated to Quantopian about whether any given investment idea, strategy, product or service described herein may be appropriate for your circumstances. All investments involve risk, including loss of principal. Quantopian makes no guarantees as to the accuracy or completeness of the views expressed in the website. The views are subject to change, and may have become unreliable for various reasons, including changes in market conditions or economic circumstances.

Hello Raymond,

If I understand your description correctly, the algorithm/backtest result isn't loading for you when you look at a backtest post.

What should be happening is that Chrome should be making a websocket request to load that backtest result. It sounds like that isn't working for you. I'd like to understand more about what is failing.

  1. In Chrome, go to the menu, and open "Tools" and turn on "Javascript Console". A toolbar will appear at the bottom.
  2. Click network in the toolbar.
  3. Reload your page.
  4. You should see something like this: screenshot. See that highlighted row? What does yours look like? I'm suspecting you get an error, or something else unexpected there.

Thanks,

Dan

@Dan
Please see the screenshot:
http://www.slickpic.com/s/3MM2z4j1zNMiIT/_201208280158/photo#1723846

As you can imagine the "Loading..." keeping unchanged in Chrome. This problem didn't happened on Firefox which's on the same PC and same time.

Thanks!

Raymond - Great screenshot. On the bottom, can you click the network button, and reproduce the problem? I want to see the websocket fail in the network tab and see why.

Its interesting that it is working for you in Firefox and not Chrome.

Hmmm. It looks like the websocket call isn't there at all. Very curious. Looking into it.

Thanks,

Hi Raymond,

Can you let us know what platform you're using Chrome on and what version it is (Wrench | About Google Chrome will tell you the version)?

Thanks.

@Jonathan It's 21.0.1180.83 m, and loading normally now. The problem could be caused by my internet or VPN connections problem which might be accidentally block certain part of the data or requests?

@Raymond Yes, it could be an internet / VPN issue, but it's also possible that it was caused by a bug in the site which we discovered and fixed last night.

doesn't work for me in chrome either. Loading all the time. I am behind a corporate firewall which could be the issue of course

The backtest graph loads over port 8001. If that port is blocked, then it won't load. That's one of those things that was "a good idea at the time" but is no longer necessary. We're going to change it to use a standard port like 443 and that should help a lot.

A quick followup - reloading brought it up. link again

Thanks for the report Brian. We were talking just yesterday about how to make that experience more robust. We put a few improvements in the list for our milestone next week.

@Jonathan Seems there're some OS problem on my computer at present. Should be test with my another renew machine soon. Hopefully will perform without any problem on it. :)

After I make a buy order, the cash and holding amount are not updated until the next few days. Is this a feature or a bug? If it is a feature, could you please explain why?

@Jame,

Thanks for taking the time to ask us about this behavior.

The behavior you are seeing is the result of the slippage model we use by default. It was originally designed for minute bar data, and the behavior is described in the FAQ:

Our backtester runs an event loop once per historical minute. Every
run of the loop loads the data for that minute and executes your
algorithm. If the algorithm calls for a buy or a sell, that order is
placed. If there are any open orders, the backtester attempts to fill
them. (Note, an order that is placed in one event loop is not filled
in that loop; it is filled in the next loop. That prevents any
look-ahead bias from leaking into your algorithm.)

The "feature" here is keeping your backtest free of lookahead bias - it ensures that your orders are not placed with knowledge of the fill price. This model works well with minutes, but comes up often as a point of confusion during day bar tests. Here is another thread where Dan Dunn is fielding the same question. Dan points out another much-needed feature: API access to your current open orders.

We are trying to consolidate the discussion of this issue in this one thread - please chime in there!

thanks,
fawce