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# `utilities` – Simple but useful Utility Functions

Tools for binary encodings

`pybrain.utilities.``one_to_n`(val, maxval)
  Returns a 1-in-n binary encoding of a non-negative integer.

`pybrain.utilities.``n_to_one`(arr)
  Returns the reverse of a 1-in-n binary encoding.

`pybrain.utilities.``int2gray`(i)
  Returns the value of an integer in Gray encoding.

`pybrain.utilities.``asBinary`(i)
  Produces a string from an integer’s binary representation. (preceding zeros removed).

Tools for sets

`pybrain.utilities.``reachable`(stepFunction, start, destinations)
  Determines the subset of destinations that can be reached from a set of starting positions, while using stepFunction (which produces a list of neighbor states) to navigate. Uses breadth-first search.

`pybrain.utilities.``crossproduct`(ss, row=None, level=0)
  Returns the cross-product of the sets given in ss.

Matrix tools

`pybrain.utilities.``triu2flat`(m)
  Flattens an upper triangular matrix, returning a vector of the non-zero elements.

`pybrain.utilities.``flat2triu`(a, dim)
  Produces an upper triangular matrix of dimension dim from the elements of the given vector.

`pybrain.utilities.``blockList2Matrix`(l)
  Converts a list of matrices into a corresponding big block-diagonal one.

`pybrain.utilities.``blockCombine`(l)
  Produce a matrix from a list of lists of its components.

Stochastic index choices

`pybrain.utilities.``drawIndex`(probs, tolerant=False)

  Draws an index given an array of probabilities.

  Key tolerant: | if set to True, the array is normalized to sum to 1.

`pybrain.utilities.``drawGibbs`(vals, temperature=1.0)
  Return the index of the sample drawn by a softmax (Gibbs).

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