{"action":"created","issue":{"url":"https://api.github.com/repos/lmfit/lmfit-py/issues/304","repository_url":"https://api.github.com/repos/lmfit/lmfit-py","labels_url":"https://api.github.com/repos/lmfit/lmfit-py/issues/304/labels{/name}","comments_url":"https://api.github.com/repos/lmfit/lmfit-py/issues/304/comments","events_url":"https://api.github.com/repos/lmfit/lmfit-py/issues/304/events","html_url":"https://github.com/lmfit/lmfit-py/issues/304","id":133828651,"number":304,"title":"allow expression with custom function in Model object","user":{"login":"Jerry-Ma","id":2752708,"avatar_url":"https://avatars.githubusercontent.com/u/2752708?v=3","gravatar_id":"","url":"https://api.github.com/users/Jerry-Ma","html_url":"https://github.com/Jerry-Ma","followers_url":"https://api.github.com/users/Jerry-Ma/followers","following_url":"https://api.github.com/users/Jerry-Ma/following{/other_user}","gists_url":"https://api.github.com/users/Jerry-Ma/gists{/gist_id}","starred_url":"https://api.github.com/users/Jerry-Ma/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/Jerry-Ma/subscriptions","organizations_url":"https://api.github.com/users/Jerry-Ma/orgs","repos_url":"https://api.github.com/users/Jerry-Ma/repos","events_url":"https://api.github.com/users/Jerry-Ma/events{/privacy}","received_events_url":"https://api.github.com/users/Jerry-Ma/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":8,"created_at":"2016-02-15T22:08:27Z","updated_at":"2016-02-17T16:17:25Z","closed_at":null,"body":"Hi, thank you for the awesome package. \r\n\r\nI just found that it would be useful if we can define custom function for defining derived parameters in Model object. Here is my thought:\r\n\r\nCurrently, the way we use model interface is as follows:\r\n    1. define a `Model` object using a model function\r\n    2. call `fit` method of the model object to obtain best fit parameters\r\n\r\nWhat step 2 does is that:\r\n    1. creates a  `ModelResult` object, which is a `Minimizer`\r\n    2. call the fitting method and update the parameters\r\n\r\nIf we can have access to the ModelRresult object before the fitting, so we can update the ast attribute to include any custom expression.\r\n"},"comment":{"url":"https://api.github.com/repos/lmfit/lmfit-py/issues/comments/185279587","html_url":"https://github.com/lmfit/lmfit-py/issues/304#issuecomment-185279587","issue_url":"https://api.github.com/repos/lmfit/lmfit-py/issues/304","id":185279587,"user":{"login":"Jerry-Ma","id":2752708,"avatar_url":"https://avatars.githubusercontent.com/u/2752708?v=3","gravatar_id":"","url":"https://api.github.com/users/Jerry-Ma","html_url":"https://github.com/Jerry-Ma","followers_url":"https://api.github.com/users/Jerry-Ma/followers","following_url":"https://api.github.com/users/Jerry-Ma/following{/other_user}","gists_url":"https://api.github.com/users/Jerry-Ma/gists{/gist_id}","starred_url":"https://api.github.com/users/Jerry-Ma/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/Jerry-Ma/subscriptions","organizations_url":"https://api.github.com/users/Jerry-Ma/orgs","repos_url":"https://api.github.com/users/Jerry-Ma/repos","events_url":"https://api.github.com/users/Jerry-Ma/events{/privacy}","received_events_url":"https://api.github.com/users/Jerry-Ma/received_events","type":"User","site_admin":false},"created_at":"2016-02-17T16:17:25Z","updated_at":"2016-02-17T16:17:25Z","body":"> So, really, I do not mean to pick on you, but I simply do not understand how this can possibly be happening. Why did you raise an Issue? What was your goal and motivation? Yes, I would really like answers to those questions.\r\nFrom my personal experience here, I would say the reason is that I was not clearly aware of the purpose of `issue tracker`. You may argue that it is clearly notified when opening a new issue, for reading the `contribute.md`, however, what happened to me was that I wasn't clear about that asking questions is called `contribute`. Of course this wouldn't happen if I have had known the mailing-list.\r\nOf course, this is not a general answer but I am sure that the diversity of maintenance styles of different repos contributes to what you saw, because I have done similar things in other places, and I mistakenly thought it applies to larger extent.\r\nIn summary, I would say as long as there is a large bulk of users who used to only `use` but some day they are trying to `contribute` or contribute,  incidents like this would be expected to happen.\r\nI suggest close the issue as off-topic."}}