[GitHub] mariussoutier opened a new issue #12409: Scala: DataDesc IllegalArgumentException with simple example

[GitBox]

mariussoutier opened a new issue #12409: Scala: DataDesc 
IllegalArgumentException with simple example
URL: https://github.com/apache/incubator-mxnet/issues/12409
 
 
   ## Description
   (Brief description of the problem in no more than 2 sentences.)
   
   Fitting using Scala and Module API throws an IAE.
   Apparently the label shape of (50) doesn't correspond to expected the NCHW 
format.
   
   ## Environment info (Required)
   
   macOS 10.13.6
   IntelliJ 2018.2.2
   Scala 2.11.12
   Java 1.8.0_121
   MXNet 1.2.1
   
   ## Error Message:
   
   ```scala
   Exception in thread "main" java.lang.IllegalArgumentException: requirement 
failed: number of dimensions in shape :1 with shape: (50) should match the 
length of the layout: 4 with layout: NCHW
        at scala.Predef$.require(Predef.scala:224)
        at org.apache.mxnet.DataDesc.<init>(IO.scala:233)
        at 
org.apache.mxnet.DataDesc$$anonfun$ListMap2Descs$1.apply(IO.scala:256)
        at 
org.apache.mxnet.DataDesc$$anonfun$ListMap2Descs$1.apply(IO.scala:256)
        at 
scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:234)
        at 
scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:234)
        at scala.collection.Iterator$class.foreach(Iterator.scala:891)
        at scala.collection.AbstractIterator.foreach(Iterator.scala:1334)
        at scala.collection.IterableLike$class.foreach(IterableLike.scala:72)
        at scala.collection.AbstractIterable.foreach(Iterable.scala:54)
        at scala.collection.TraversableLike$class.map(TraversableLike.scala:234)
        at scala.collection.AbstractTraversable.map(Traversable.scala:104)
        at org.apache.mxnet.DataDesc$.ListMap2Descs(IO.scala:256)
        at org.apache.mxnet.module.BaseModule.fit(BaseModule.scala:399)
   ```
   
   
   ## Minimum reproducible example
   
   ```scala
       val trainDataIter = IO.ImageRecordIter(Map(
         "data_name" -> dataName,
         "path_imgrec" -> this.getClass.getResource("/data/mydata.rec").getFile,
         "data_shape" -> "(3,128,128)",
         "batch_size" -> "50"
       ))
   
   val mod = new Module(mlp)
       mod.fit(
         trainDataIter,
         Some(testDataIter),
         numEpoch = 10,
         fitParams =
           new FitParams()
             .setOptimizer(new SGD(0.1f, 0.9f, 0.0001f))
       )
   ```
   
   Tried debugging this, but pretty difficult to find out what's going on with 
a stringly typed API.
   
   `println(trainDataIter.provideData)` -> Map(data -> (50,3,128,128))
   `println(trainDataIter.provideLabel)` -> Map(label -> (50))
   

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