Module « scipy.spatial.distance »

Fonction squareform - module scipy.spatial.distance

Signature de la fonction squareform

def squareform(X, force='no', checks=True) 

Description

squareform.__doc__

    Convert a vector-form distance vector to a square-form distance
    matrix, and vice-versa.

    Parameters
    ----------
    X : array_like
        Either a condensed or redundant distance matrix.
    force : str, optional
        As with MATLAB(TM), if force is equal to ``'tovector'`` or
        ``'tomatrix'``, the input will be treated as a distance matrix or
        distance vector respectively.
    checks : bool, optional
        If set to False, no checks will be made for matrix
        symmetry nor zero diagonals. This is useful if it is known that
        ``X - X.T1`` is small and ``diag(X)`` is close to zero.
        These values are ignored any way so they do not disrupt the
        squareform transformation.

    Returns
    -------
    Y : ndarray
        If a condensed distance matrix is passed, a redundant one is
        returned, or if a redundant one is passed, a condensed distance
        matrix is returned.

    Notes
    -----
    1. ``v = squareform(X)``

       Given a square n-by-n symmetric distance matrix ``X``,
       ``v = squareform(X)`` returns a ``n * (n-1) / 2``
       (i.e. binomial coefficient n choose 2) sized vector `v`
       where :math:`v[{n \choose 2} - {n-i \choose 2} + (j-i-1)]`
       is the distance between distinct points ``i`` and ``j``.
       If ``X`` is non-square or asymmetric, an error is raised.

    2. ``X = squareform(v)``

       Given a ``n * (n-1) / 2`` sized vector ``v``
       for some integer ``n >= 1`` encoding distances as described,
       ``X = squareform(v)`` returns a n-by-n distance matrix ``X``.
       The ``X[i, j]`` and ``X[j, i]`` values are set to
       :math:`v[{n \choose 2} - {n-i \choose 2} + (j-i-1)]`
       and all diagonal elements are zero.

    In SciPy 0.19.0, ``squareform`` stopped casting all input types to
    float64, and started returning arrays of the same dtype as the input.