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August 29, 2015 14:26
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Translation of the script from this blog post: http://iamtrask.github.io/2015/07/12/basic-python-network/ from python and numpy to scala and nd4j (http://nd4j.org/).
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| import org.nd4j.api.linalg.DSL._ | |
| import org.nd4j.linalg.api.ndarray.INDArray | |
| import org.nd4j.linalg.factory.Nd4j | |
| import org.nd4j.linalg.lossfunctions.LossFunctions | |
| import org.nd4j.linalg.ops.transforms.Transforms | |
| /** | |
| * Created by nmiano on 7/27/15. | |
| */ | |
| object App { | |
| def layer(rows: Int, cols: Int): INDArray = (Nd4j.rand(rows, cols) * 2) - 1 | |
| def main(args: Array[String]): Unit = { | |
| val X = Nd4j.create(Array[Array[Float]]( | |
| Array[Float](0, 0, 1), | |
| Array[Float](0, 1, 1), | |
| Array[Float](1, 0, 1), | |
| Array[Float](1, 1, 1))) | |
| val y = Nd4j.create(Array[Float](0, 1, 1, 0), Array[Int](4, 1)) | |
| val syn0 = layer(3, 4) | |
| val syn1 = layer(4, 1) | |
| //train | |
| (0 until 60000).foreach((j) => { | |
| //feed forward | |
| val l0 = X | |
| val l1 = Transforms.sigmoid(l0.dot(syn0)) | |
| val l2 = Transforms.sigmoid(l1.dot(syn1)) | |
| //how much did we miss the target value? | |
| val l2Error = y - l2 | |
| //logging | |
| if (j % 10000 == 0) println("Error: " + Transforms.abs(Nd4j.mean(l2Error))) | |
| //in what direction is the target value? | |
| //were we really sure? if so, don't change too much. | |
| val l2Delta = l2Error * (l2 * ((l2 * (-1)) + 1)) | |
| //how much did each l1 value contribute to the l2 error (according to the weights)? | |
| val l1Error = l2Delta.dot(syn1.T) | |
| //in what direction is the target l1? | |
| //were we really sure? if so, don't change too much. | |
| val l1Delta = l1Error * (l1 * ((l1 * (-1)) + 1)) | |
| syn1 += l1.T.dot(l2Delta) | |
| syn0 += l0.T.dot(l1Delta) | |
| }) | |
| //playing around with it | |
| val n0 = Nd4j.create(Array[Float](0, 1, 1)) | |
| val n1 = Transforms.sigmoid(n0.dot(syn0)) | |
| val n2 = Transforms.sigmoid(n1.dot(syn1)) | |
| println(n2) | |
| val z0 = Nd4j.create(Array[Float](1, 1, 1)) | |
| val z1 = Transforms.sigmoid(z0.dot(syn0)) | |
| val z2 = Transforms.sigmoid(z1.dot(syn1)) | |
| println(z2) | |
| } | |
| } |
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