scripts/builtin/toOneHot.dml

#-------------------------------------------------------------
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#-------------------------------------------------------------

# The toOneHot-function encodes unordered categorical vector to multiple binary vectors.
#
# .. code-block:: python
#
#   >>> import numpy as np
#   >>> from systemds.context import SystemDSContext
#   >>> from systemds.operator.algorithm import toOneHot
#   >>> 
#   >>> with SystemDSContext() as sds:
#   ...     X = sds.from_numpy(np.array([[1], [3], [2], [3]]))
#   ...     Y = toOneHot(X, numClasses=3).compute()
#   ...     print(Y)
#   [[1. 0. 0.]
#    [0. 0. 1.]
#    [0. 1. 0.]
#    [0. 0. 1.]]
#
#
# INPUT:
# ------------------------------------------------------------------------------------------
# X           Vector with N integer entries between 1 and numClasses
# numclasses  Number of columns, must be be greater than or equal to largest value in X
# ------------------------------------------------------------------------------------------
#
# OUTPUT:
# ------------------------------------------------------------------------------------
# Y     One-hot-encoded matrix with shape (N, numClasses)
# ------------------------------------------------------------------------------------

m_toOneHot = function(Matrix[Double] X, integer numClasses)
        return (Matrix[Double] Y) {
    if(numClasses < max(X))
      stop("numClasses must be >= largest value in X to prevent cropping");
    Y = table(seq(1, nrow(X)), X, nrow(X), numClasses);
}