Monthly Archives: August 2013

Mapper and the choice of scale

In last week’s post, I described the DBSCAN clustering algorithm, which uses the notion of density to determine which data points in a data set form tightly packed groups called clusters. This algorithm relies on two parameters – a distance … Continue reading

Posted in Clustering, Unsupervised learning | 4 Comments

Clusters and DBScan

A few weeks ago, I mentioned the idea of a clustering algorithm, but here’s a recap of the idea: Often, a single data set will be made up of different groups of data points, each of which corresponds to a … Continue reading

Posted in Clustering, Unsupervised learning | 7 Comments

Graphs and networks

In last week’s post, I discussed the difference between the extrinsic and intrinsic structures of a data set. The extrinsic structure, which has to do with how the data points sit in the data space, is encoded by the vector … Continue reading

Posted in Uncategorized | 2 Comments

Intrinsic vs. Extrinsic Structure

At this point, I think it will be useful to introduce an idea from geometry that is very helpful in pure mathematics, and that I find helpful for understanding the geometry of data sets. This idea is difference between the … Continue reading

Posted in Unsupervised learning | 6 Comments