python - How to get the samples in each cluster?

Question

I am using the sklearn.cluster KMeans package. Once I finish the clustering if I need to know which values were grouped together how can I do it?

Say I had 100 data points and KMeans gave me 5 cluster. Now I want to know which data points are in cluster 5. How can I do that.

Is there a function to give the cluster id and it will list out all the data points in that cluster?

Answer 1

I had a similar requirement and i am using pandas to create a new dataframe with the index of the dataset and the labels as columns.

data = pd.read_csv('filename')

km = KMeans(n_clusters=5).fit(data)

cluster_map = pd.DataFrame()
cluster_map['data_index'] = data.index.values
cluster_map['cluster'] = km.labels_

Once the DataFrame is available is quite easy to filter, For example, to filter all data points in cluster 3

cluster_map[cluster_map.cluster == 3]