# Questions tagged [data-mining]

This tag is for questions about data mining, which is an interdisciplinary subfield of computer science. It is the computational process of discovering patterns in large data sets.

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### How do I find the formula (or rules) that created a list of numbers with seemingly no pattern?

Newbie here, and I apologize if this is the wrong forum for this type of question... I have a group of 200 or so alphanumeric codes from an unknown source. Here's an example piece of the data set: <...
6k views

### Normalization of data in decision tree

After reading through a few references, I have come to know that for machine learning in general, it is necessary to normalize features so that no features are arbitrarily large ($centering$) and all ...
5k views

### Mutual Information for clustering

I'm working on a document clustering application and decided to use Normalized Mutual Information as one of the measures of effectivenes. But I don't really understand how to implement this in that ...
66 views

### How to find almost periodic lattices in a set of high-dimensional points?

sorry for lame question, but I just have no maturity in this direction. Let's say I have very large set ( millions ) of high-dimensional vectors ( typical dimensionality is 64). These vectors ...
516 views

### What is KL-Divergence? Why Do I need it? How do I use it?

I am currently studying KL Divergence. But It seems very confusing that I don't maybe understand why do I ever need it and what is that for? As I have been reading stuff about Mutual Information, it ...
1k views

### Distance between unequal-dimension vectors (and data)?

It is easy to find simple distance measures for equal-dimension vectors, such as Euclidean Distance or Correlation. What about unequal-dimension vectors, such as, for instance, $(a,b,c)$ and $(d,e)$? ...
2k views

### How can one prove that mahalanobis distance is a metric?

How can one prove that mahalanobis distance is a metric? How can one show that these four properties of a metric are valid for mahalanobis distance? 1) d(x, y) ≥ 0 (non-negativity, or separation ...
46 views

### Number of rules (Data Mining)

This is a paraphrasing of a statement from Data Mining by Witten et al., 4th edition, on section 1.6. Consider the set $S = \{1, \dots, 288\}$. A rule is defined as a one-element singleton set ...
236 views

### Does there exist closed-form solutions for calculations in the EM-algorithm for Gaussian Mixtures?

Our data can be represented as $X_{n\times d}$ matrix, where we have $n$ data points lying in $\mathbb{R}^d$. We assume that there are $k$ underlying Gaussian models, $\mathcal{N}_d(\mu_j, \Sigma_j)$, ...
37 views

### Clustering elements according to covariance matrix

I'm doing a little bit of topic modelling (which is not really my area) with twitter tweets. The situation is the following: I have a (sort of) covariance matrix where the entrie $C_{ij}$ corresponds ...