{"action":"created","issue":{"url":"https://api.github.com/repos/dmlc/mxnet/issues/3043","repository_url":"https://api.github.com/repos/dmlc/mxnet","labels_url":"https://api.github.com/repos/dmlc/mxnet/issues/3043/labels{/name}","comments_url":"https://api.github.com/repos/dmlc/mxnet/issues/3043/comments","events_url":"https://api.github.com/repos/dmlc/mxnet/issues/3043/events","html_url":"https://github.com/dmlc/mxnet/issues/3043","id":171530530,"number":3043,"title":"Problem with WarpCTC design","user":{"login":"sbodenstein","id":10237782,"avatar_url":"https://avatars.githubusercontent.com/u/10237782?v=3","gravatar_id":"","url":"https://api.github.com/users/sbodenstein","html_url":"https://github.com/sbodenstein","followers_url":"https://api.github.com/users/sbodenstein/followers","following_url":"https://api.github.com/users/sbodenstein/following{/other_user}","gists_url":"https://api.github.com/users/sbodenstein/gists{/gist_id}","starred_url":"https://api.github.com/users/sbodenstein/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/sbodenstein/subscriptions","organizations_url":"https://api.github.com/users/sbodenstein/orgs","repos_url":"https://api.github.com/users/sbodenstein/repos","events_url":"https://api.github.com/users/sbodenstein/events{/privacy}","received_events_url":"https://api.github.com/users/sbodenstein/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"assignees":[],"milestone":null,"comments":1,"created_at":"2016-08-16T22:11:09Z","updated_at":"2016-08-17T01:58:13Z","closed_at":null,"body":"@xlvector @antinucleon: currently, there is no clean way to feed tensors of shape `[sequence, batch, feature size]` into WarpCTC: it only takes `[sequence x batch, feature size]`, and there is no nice syntax with Reshape to produce this form from `[sequence, batch, feature size]` (Reshape layer doesn't have a nice way of doing this. You need to explicitly state the sequence + batch size, which makes executor reshaping ugly). \r\n\r\n`[sequence x batch, feature size]` is also very confusing to people, as they don't know what order batch and sequence appear in for the underlying data. In addition, they need to specify the sequence length (\"input_length\") and label length explicitly, which would just be inferred from the input tensor if you used  `[sequence, batch, feature size]`.\r\n\r\nSo: should we change `[sequence x batch, feature size]` to  `[sequence, batch, feature size]` and break backward compatibility, or just add support for Rank-3 inputs that will be interpreted as  `[sequence, batch, feature size]`?"},"comment":{"url":"https://api.github.com/repos/dmlc/mxnet/issues/comments/240292935","html_url":"https://github.com/dmlc/mxnet/issues/3043#issuecomment-240292935","issue_url":"https://api.github.com/repos/dmlc/mxnet/issues/3043","id":240292935,"user":{"login":"xlvector","id":100203,"avatar_url":"https://avatars.githubusercontent.com/u/100203?v=3","gravatar_id":"","url":"https://api.github.com/users/xlvector","html_url":"https://github.com/xlvector","followers_url":"https://api.github.com/users/xlvector/followers","following_url":"https://api.github.com/users/xlvector/following{/other_user}","gists_url":"https://api.github.com/users/xlvector/gists{/gist_id}","starred_url":"https://api.github.com/users/xlvector/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/xlvector/subscriptions","organizations_url":"https://api.github.com/users/xlvector/orgs","repos_url":"https://api.github.com/users/xlvector/repos","events_url":"https://api.github.com/users/xlvector/events{/privacy}","received_events_url":"https://api.github.com/users/xlvector/received_events","type":"User","site_admin":false},"created_at":"2016-08-17T01:58:13Z","updated_at":"2016-08-17T01:58:13Z","body":"I think current lstm example in examples/rnn also use shape [sequence x batch, feature size]. When I implement ctc, I just follow it.\r\n\r\nHowever, I think you suggestion is good, I was also confused about this (sequence and batch which should be first?) before.\r\n\r\n@antinucleon "}}
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