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Scala nd4j examples
package org.deeplearning4j.learn
import java.util.Arrays
import org.nd4j.api.linalg.DSL._
import org.nd4j.linalg.api.ndarray.INDArray
import org.nd4j.linalg.factory.Nd4j
import org.nd4j.linalg.indexing.{NDArrayIndex, BooleanIndexing}
import org.nd4j.linalg.indexing.conditions.Conditions
import org.nd4j.linalg.indexing.functions.Value
import org.nd4j.linalg.ops.transforms.Transforms._
/**
* Examples of Scala Nd4j usage
*
* Before using Scala Nd4j, make sure you have included the nd4j-scala-api Maven dependency
* Ensure you have the Scala plugin (IntelliJ: Preferences -> Plugins)
* Add Maven Scala plugin and plugin repository to pom.xml
*
*
* @author sonali
*/
object Nd4jScalaExamples {
def main (args: Array[String]) {
/** Creating arrays in multiple ways, all using numpy syntax */
var arr = Nd4j.create(4)
var arr2 = Nd4j.ones(4)
val arr3 = Nd4j.linspace(1, 10, 10)
val arr4 = Nd4j.linspace(1, 6, 6).reshape(2, 3)
/** Array addition in place */
arr += arr2
arr += 2
/** Array multiplication in place */
arr2 *= 5
/** Transpose matrix */
val arrT = arr.T
/** Row (0) and Column (1) Sums */
println(Nd4j.sum(arr4, 0).toString + "Calculate the sum for each row")
println(Nd4j.sum(arr4, 1).toString + "Calculate the sum for each column")
/** Checking array shape */
println(Arrays.toString(arr2.shape) + "Checking array shape")
/** Converting array to a string */
println(arr2.toString() + "Array converted to string")
/** Filling the array with the value 5 (same as numpy's fill method) */
println(arr2.assign(5).toString + "Array assigned value of 5 (equivalent to fill method in numpy)")
/** Reshaping the array */
println(arr2.reshape(2, 2).toString + "Reshaping array")
/** Raveling the array (returns a flattened array) */
println(arr2.ravel.toString + "Raveling array")
/** Flattening the array (same as numpy's flatten method) */
println(Nd4j.toFlattened(arr2).toString + "Flattening array (equivalent to flatten in numpy)")
/** Array sorting */
println(Nd4j.sort(arr2, 0, true).toString + "Sorting array")
println(Nd4j.sortWithIndices(arr2, 0, true).toString + "Sorting array and returning sorted indices")
/** Cumulative sum */
println(Nd4j.cumsum(arr2).toString + "Cumulative sum")
/** Basic stats methods */
println(Nd4j.mean(arr).toString + "Calculate mean of array")
println(Nd4j.std(arr2).toString + "Calculate standard deviation of array")
println(Nd4j.`var`(arr2).toString, "Calculate variance")
/** Find min and max values */
println(Nd4j.max(arr3), "Find max value in array")
println(Nd4j.min(arr3), "Find min value in array")
/** Boolean indexing */
/** Where a given condition holds true, apply a function to an NDArray */
/** In this example, replace any values below 5 with 5 */
BooleanIndexing.applyWhere(arr3, Conditions.lessThan(5), new Value(5))
/** In this example, replace any NaN values with 0 */
BooleanIndexing.applyWhere(arr3, Conditions.isNan, new Value(0))
/** Use .and for conditions that must be true for all elements in the array */
if (BooleanIndexing.and(arr3, Conditions.greaterThan(0))) {
println("All elements in array are greater than 0.")
}
/** Use .or for conditions that must be true for AT LEAST one element in the array */
if (BooleanIndexing.or(arr3, Conditions.lessThanOrEqual(5))) {
println("At least one element in array is less than or equal to 5.")
}
/** Use NDArrayIndex for indexing/slicing an array */
val arr3Slice: INDArray = arr3.get(NDArrayIndex.interval(1, 5))
}
}
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