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Add a tutorial for control flow operators. #12340
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sandeep-krishnamurthy
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@aaronmarkham could you review this tutorial, please? |
aaronmarkham
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Aug 25, 2018
| MXNet currently provides three control flow operators: `cond`, `foreach` and `while_loop`. Like other MXNet operators, they all have a version for NDArray and a version for Symbol. These two versions have exactly the same semantics. We can take advantage of this and use them in Gluon to hybridize models. | ||
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| In this tutorial, we use a few examples to demonstrate the use of control flow operators in Gluon and show how a model that requires control flow is hybridized. | ||
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Are there any prerequisites worth mentioning?
| foreach(body, data, init_states, name) => (outputs, states) | ||
| ``` | ||
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| It iterates over the first dimension of the input data (it can be an array or a list of arrays) and run the Python function defined in `body` for every slice from the input arrays. The signature of the `body` function is defined as follows: |
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| The inputs of the `body` function have two parts: `data` is a slice of an array (if there is only one input array in `foreach`) or a list of slices (if there are a list of input arrays); `states` are the arrays from the previous iteration. The outputs of the `body` function also have two parts: `outputs` is an array or a list of arrays; `states` is the computation states of the current iteration. `outputs` from all iterations are concatenated as the outputs of `foreach`. | ||
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| The pseudocode below illustrates the execution of `foreach`. |
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use "the following" instead of below (different consumption modes means the content isn't always below)
| ``` | ||
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| ### Example 1: foreach works like map | ||
| `foreach` can work like a map function of a functional language. In this case, the states of foreach can be an empty list, which means the computation doesn't carry computation states across iterations. |
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tick each use of foreach
| ### Example 1: foreach works like map | ||
| `foreach` can work like a map function of a functional language. In this case, the states of foreach can be an empty list, which means the computation doesn't carry computation states across iterations. | ||
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| In this example, we use `foreach` to add each element in an array by one. |
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use foreach with an array to increase each element's value by one
| ``` | ||
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| ```python |
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why two different code blocks? Is there supposed to be some commentary here?
| from mxnet.gluon import HybridBlock | ||
| ``` | ||
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| # foreach |
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I'd go to two hashes for your subsections and only use the single hash for the document title.
| res, states = lstm(rnn_data, [x for x in init_states], valid_length) | ||
| ``` | ||
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| # while_loop |
| <NDArray 1 @cpu(0)>] | ||
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| # cond |
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| # cond | ||
| `cond` is defined with the following signature: |
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It would be nice to talk about what it is and what it does before showing the signature. The same goes for the other sections/functions.
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Will this be added to http://mxnet.incubator.apache.org/tutorials/index.html ?
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@zheng-da @eric-haibin-lin @aaronmarkham Can you check if all the feebdack was addressed and is this PR ready to merge now? |
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my comments are addressed |
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@Roshrini I have addressed all of @aaronmarkham's comments. |
Roshrini
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Aug 27, 2018
* the first version. * fix. * add to test. * fix. * fix. * fix * fix. * fix. * add title. * add link * fix.
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szha
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Aug 27, 2018
* Add a tutorial for control flow operators. (#12340) * the first version. * fix. * add to test. * fix. * fix. * fix * fix. * fix. * add title. * add link * fix. * Update ONNX API docs references (#12317) * update onnx API references * update descriptions * [MXAPPS-581] Disable an additional long test in the SD nightly (#12343) * Disable an additional test in the SD nightly that also takes over the timeout. * Documentation update related to sparse support (#12367) * Update sparse.md * Update sparse.md * Update csr.md * Update row_sparse.md * Update train.md
anirudh2290
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Sep 19, 2018
* the first version. * fix. * add to test. * fix. * fix. * fix * fix. * fix. * add title. * add link * fix.
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Description
This is to provide a tutorial for control flow operators.
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