{"action":"created","issue":{"url":"https://api.github.com/repos/benanne/Lasagne/issues/127","labels_url":"https://api.github.com/repos/benanne/Lasagne/issues/127/labels{/name}","comments_url":"https://api.github.com/repos/benanne/Lasagne/issues/127/comments","events_url":"https://api.github.com/repos/benanne/Lasagne/issues/127/events","html_url":"https://github.com/benanne/Lasagne/pull/127","id":56348921,"number":127,"title":"Objectives now have an optional mask.","user":{"login":"Britefury","id":897534,"avatar_url":"https://avatars.githubusercontent.com/u/897534?v=3","gravatar_id":"","url":"https://api.github.com/users/Britefury","html_url":"https://github.com/Britefury","followers_url":"https://api.github.com/users/Britefury/followers","following_url":"https://api.github.com/users/Britefury/following{/other_user}","gists_url":"https://api.github.com/users/Britefury/gists{/gist_id}","starred_url":"https://api.github.com/users/Britefury/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/Britefury/subscriptions","organizations_url":"https://api.github.com/users/Britefury/orgs","repos_url":"https://api.github.com/users/Britefury/repos","events_url":"https://api.github.com/users/Britefury/events{/privacy}","received_events_url":"https://api.github.com/users/Britefury/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":10,"created_at":"2015-02-03T08:42:38Z","updated_at":"2015-02-07T13:48:43Z","closed_at":null,"pull_request":{"url":"https://api.github.com/repos/benanne/Lasagne/pulls/127","html_url":"https://github.com/benanne/Lasagne/pull/127","diff_url":"https://github.com/benanne/Lasagne/pull/127.diff","patch_url":"https://github.com/benanne/Lasagne/pull/127.patch"},"body":"Masked objectives allow specified rows to be ignored when computing the loss value. For classification problems, this can be useful if training or test set is not an exact multiple of the mini-batch size; on the last mini-batch you provide a mask with zeros for the entries in the mini-batch for which you do not have data. For image segmentation problems the mask can be used to define a region of interest."},"comment":{"url":"https://api.github.com/repos/benanne/Lasagne/issues/comments/73364922","html_url":"https://github.com/benanne/Lasagne/pull/127#issuecomment-73364922","issue_url":"https://api.github.com/repos/benanne/Lasagne/issues/127","id":73364922,"user":{"login":"benanne","id":43829,"avatar_url":"https://avatars.githubusercontent.com/u/43829?v=3","gravatar_id":"","url":"https://api.github.com/users/benanne","html_url":"https://github.com/benanne","followers_url":"https://api.github.com/users/benanne/followers","following_url":"https://api.github.com/users/benanne/following{/other_user}","gists_url":"https://api.github.com/users/benanne/gists{/gist_id}","starred_url":"https://api.github.com/users/benanne/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/benanne/subscriptions","organizations_url":"https://api.github.com/users/benanne/orgs","repos_url":"https://api.github.com/users/benanne/repos","events_url":"https://api.github.com/users/benanne/events{/privacy}","received_events_url":"https://api.github.com/users/benanne/received_events","type":"User","site_admin":false},"created_at":"2015-02-07T13:48:43Z","updated_at":"2015-02-07T13:48:43Z","body":"That's definitely an improvement, but as we discussed on this PR before, I feel we need some more fundamental changes to handle this cleanly.\r\n\r\nWe should modify the interface of the objective functions so they don't compute the mean across examples (at the very least), then we can implement the masking once and use it in conjunction with all of them, instead of having to add masking logic to every objective function separately."}}