scripts/builtin/dist.dml

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

# Returns Euclidean distance matrix (distances between N n-dimensional points)
#
# .. code-block:: python
#
#   >>> import numpy as np
#   >>> from systemds.context import SystemDSContext
#   >>> from systemds.operator.algorithm import dist
#   >>> 
#   >>> with SystemDSContext() as sds:
#   ...     X = sds.from_numpy(np.array([[0], [3], [4]]))
#   ...     out = dist(X).compute()
#   ...     print(out)
#   [[0. 3. 4.]
#    [3. 0. 1.]
#    [4. 1. 0.]]
#
#
# INPUT:
# --------------------------------------------------------------------------------
# X       Matrix to calculate the distance inside
# --------------------------------------------------------------------------------
#
# OUTPUT:
# -----------------------------------------------------------------------------------------------
# Y      Euclidean distance matrix
# -----------------------------------------------------------------------------------------------

m_dist = function(Matrix[Double] X) return (Matrix[Double] Y) {
  n = nrow(X)
  s = rowSums(X^2)
  Y = sqrt(-2 * X %*% t(X) + s + t(s))
  Y = replace(target = Y, pattern=NaN, replacement = 0);
}