k-means k均值聚类的弱点/缺点
Similar to other algorithm, K-mean clustering has many weaknesses:
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1 When the numbers of data are not so many, initial grouping will determine the cluster significantly.? 當數據數量不是足夠大時,初始化分組很大程度上決定了聚類,影響聚類結果。
2 The number of cluster, K, must be determined before hand.? 要事先指定K的值。
3 We never know the real cluster, using the same data, if it is inputted in a different order may produce different cluster if the number of data is a few. 數據數量不多時,輸入的數據的順序不同會導致結果不同。
4 Sensitive to initial condition. Different initial condition may produce different result of cluster. The algorithm may be trapped in the local optimum. 對初始化條件敏感。
5 We never know which attribute contributes more to the grouping process since we assume that each attribute has the same weight. 無法確定哪個屬性對聚類的貢獻更大。
6 weakness of arithmetic mean is not robust to outliers. Very far data from the centroid may pull the centroid away from the real one. 使用算術平均值對outlier不魯棒。
7 The result is circular cluster shape because based on distance.? 因為基于距離,故結果是圓形的聚類形狀。
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One way to overcome those weaknesses is to use K-mean clustering only if there are available many data. To overcome outliers problem, we can use median instead of mean.? 克服缺點的方法: 使用盡量多的數據;使用中位數代替均值來克服outlier的問題。
Some people pointed out that K means clustering cannot be used for other type of data rather than quantitative data. This is not true! See how you can use multivariate data up to n dimensions (even mixed data type) here. The key to use other type of dissimilarity is in the distance matrix.
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http://people.revoledu.com/kardi/tutorial/kMean/Weakness.htm
轉載于:https://www.cnblogs.com/emanlee/archive/2012/03/06/2381617.html
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