Package opennlp.tools.ml
Class ArrayMath
java.lang.Object
opennlp.tools.ml.ArrayMath
Utility class for simple vector arithmetic.
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionstatic intargmax(double[] x) Finds the index of the maximum element in a vectorxstatic doubleinnerProduct(double[] vecA, double[] vecB) static doubleinvL2norm(double[] v) Computes the Inverse L2-norm for a vectorv.static doublel1norm(double[] v) Computes the L1-norm for a vectorv.static doublel2norm(double[] v) Computes the L2-norm for a vectorv.static doublelogSumOfExps(double[] x) Computes\log(\sum_{i=1}^n e^{x_i})using a maximum-element trick to avoid arithmetic overflow.static doublemax(double[] x) Finds the maximum element in a vectorx.static voidsumFeatures(Context[] context, float[] values, double[] prior) static double[]toDoubleArray(List<Double> list) Convert a list ofDoubleobjects into an array of primitive doubles.static int[]toIntArray(List<Integer> list) Convert a list ofIntegerobjects into an array of primitive integers.
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Constructor Details
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ArrayMath
public ArrayMath()
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Method Details
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innerProduct
public static double innerProduct(double[] vecA, double[] vecB) -
l1norm
public static double l1norm(double[] v) Computes the L1-norm for a vectorv.- Parameters:
v- The vector ofdoublevalues.- Returns:
- The computed L1-norm.
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l2norm
public static double l2norm(double[] v) Computes the L2-norm for a vectorv.- Parameters:
v- The vector ofdoublevalues.- Returns:
- The computed L2-norm.
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invL2norm
public static double invL2norm(double[] v) Computes the Inverse L2-norm for a vectorv.- Parameters:
v- The vector ofdoublevalues.- Returns:
- The computed Inverse L2-norm.
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logSumOfExps
public static double logSumOfExps(double[] x) Computes\log(\sum_{i=1}^n e^{x_i})using a maximum-element trick to avoid arithmetic overflow.- Parameters:
x- The vector ofdoublevalues.- Returns:
- The log-sum of exponentials of vector elements.
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max
public static double max(double[] x) Finds the maximum element in a vectorx.- Parameters:
x- The vector ofdoublevalues.- Returns:
- The maximum element in
x.
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argmax
public static int argmax(double[] x) Finds the index of the maximum element in a vectorx- Parameters:
x- The vector ofdoublevalues.- Returns:
- The index of the maximum element. Index of the first maximum element is returned if multiple maximums are found.
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sumFeatures
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toDoubleArray
Convert a list ofDoubleobjects into an array of primitive doubles.- Parameters:
list- The input vector ofvalues.- Returns:
- The
double[].
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toIntArray
Convert a list ofIntegerobjects into an array of primitive integers.- Parameters:
list- The input vector ofvalues.- Returns:
- The
int[].
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