scipy.spatial.distance.squareform¶
-
scipy.spatial.distance.
squareform
(X, force='no', checks=True)[source]¶ Convert a vector-form distance vector to a square-form distance matrix, and vice-versa.
- Parameters
- Xndarray
Either a condensed or redundant distance matrix.
- forcestr, 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.- checksbool, 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 anddiag(X)
is close to zero. These values are ignored any way so they do not disrupt the squareform transformation.
- Returns
- Yndarray
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
v = squareform(X)
Given a square d-by-d symmetric distance matrix X,
v = squareform(X)
returns ad * (d-1) / 2
(or \({n \choose 2}\)) sized vector v.
\(v[{n \choose 2}-{n-i \choose 2} + (j-i-1)]\) is the distance between points i and j. If X is non-square or asymmetric, an error is returned.
X = squareform(v)
Given a
d*(d-1)/2
sized v for some integerd >= 2
encoding distances as described,X = squareform(v)
returns a d by d distance matrix X. TheX[i, j]
andX[j, i]
values are set to \(v[{n \choose 2}-{n-i \choose 2} + (j-i-1)]\) 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.