title: KNN when using a precomputed affinity matrix in Scikit's spectral clustering?
body: <p>I have a similarity matrix that I have calculated between a large number of objects, and each object can have a non-zero similarity with any other object. I generated this matrix for another task, and would now like to cluster it for a new analysis.</p>
  
  <p>It seems like <a href="http://scikit-learn.org/stable/modules/generated/sklearn.cluster.SpectralClustering.html#sklearn.cluster.SpectralClustering" rel="nofollow">scikit's spectral clustering</a> method could be a good fit, because I can pass in a precomputed affinity matrix. I also know that spectral clustering typically uses some number of nearest neighbors when building the affinity matrix, and my similarity matrix does not have that same constraint.</p>
  
  <p>If I pass in a matrix that allows any number of edges between nodes in the affinity matrix, will scikit limit each node to having only a certain number of nearest neighbors? If not, I guess I will have to make that change to my pre-computed affinity matrix.</p>