Davies Bouldin index

The  Davies�CBouldin index (DBI) is a metric for evaluating  clustering algorithms. [1]
Let  Ci be a cluster of vectors. Let  Xj be a vector on  Ci.
Here  Ai is the centroid of  CiSi is a measure of scatter within the cluster.
 M_{i,j} = \sqrt[p]{\displaystyle\sum_{k=1}^{N}\left|a_{k,i}-a_{k,j}\right|^p }
Mi,j is a measure of separation between cluster  Ci and cluster  Cj.
ak,i is the  kth element of  Ai.
 R_{i,j} \equiv \frac{S_i+S_j}{M_{i,j}}
 R_i \equiv \max_{j : i \neq j} R_{i,j}
 \bar{R} \equiv \frac{1}{N}\displaystyle\sum_{i=1}^N R_i

[edit]Notes and references

  1. ^ Davies, D. L.; Bouldin, D. W. A cluster separation measure.IEEE Trans. Pattern Anal. Mach. Intelligence 1979, 1, 224�C227. 论文见附件

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