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-3
votes
0answers
24 views

How do you use python to project a grid of pixels from a FITS file using pyFITS onto another grid by applying resampling between the pixels? [on hold]

I want to setup grid on the sky by reading the header of a FITS file and figure out the right ascension (RA) and declination (DEC) each pixel corresponds to. Then for each pixel of the grid, figure ...
0
votes
0answers
20 views

Mathematics of simple performance testing [migrated]

I have a set of sorted tables T that have known but different dimensions. There are two types of functions in this system: f(T) g(T, n), where n is an integer parameter. ... and two types of costs ...
0
votes
0answers
89 views

Database of non-isomorphic trees

As there are several free prime number databases, is there something similar for non-isomorphic trees?
4
votes
0answers
232 views

Implications of a recent result on Benford's law

I want to the discuss the implications of a theorem by J. Morrow (2010) regarding Benford's law. There are many papers written about Benford's law with a comprenhensive discussion of the advantages ...
16
votes
4answers
1k views

Inference using Topological Data Analysis: Is it worth it for a regular statistician to learn TDA?

After having read Gunnar Carlsson's http://www.ams.org/journals/bull/2009-46-02/S0273-0979-09-01249-X/S0273-0979-09-01249-X.pdf I feel enthusiastic to use some topological data analysis (TDA) methods ...
8
votes
2answers
581 views

Easier reference for material like Diaconis's “Group representations in probability and statistics”

I'm teaching a class on the representation theory of finite groups at the advanced undergrad level. One of the things I'd like to talk about, or possibly have a student do any independent project on ...
1
vote
2answers
194 views

Appropriate histogram comparison distance measure

I am working with hyperspectral image data in R, so I have subset an image to a region of 5000 pixels, each containing a vector 254 bands in length. I would like to cluster this data in order to try ...
2
votes
1answer
396 views

correlation for three variables? [closed]

suppose we have three variables here, x,y, z now, what we know is that the correlation between x and z is 0.6, the correlation between y and z is 0.65. Here is the question, is there any formula to ...
0
votes
0answers
95 views

Unusual function computation in signal processing

Hi, I wonder if there is 'an operation' that allow me to compute this special function faster than square-time $O(n^2)$. Assume we have functions $f(x)$ and $h(x)$. $h(x)$ has a special point ...
0
votes
2answers
374 views

Interpolating a “manifold” between two points

Edit: I have reworded the question. This may be a basic question but I am having trouble figuring out the correct answer. I want to find a local coordinate chart that fits a d-dimensional ...
9
votes
3answers
1k views

Higher categories as data structures

Still wading through higher category theory. I find the subject a bit intimidating, not so much for technical reasons, but because I lack sufficient intuition as to the motivation(s)/heuristics one ...
0
votes
0answers
89 views

Extrapolate trend in gridded data

I'm interested in extrapolating measured horizontal wind data of a vehicle into a forecast horizontal wind grid. Given the flight path you have a series of points that are "more accurate" than the ...
2
votes
0answers
108 views

isomap and self intersections

I sample a 2D surface in $\mathbb{R}^3$ with $N$ points, and compute an isomap using pairwise weighted geodesic distances. I am thus able to embed this surface into a $M$ dimensional space in which ...
5
votes
2answers
828 views

Solving for Moore Penrose pseudo inverse

I have a system to solve, set up as : $$Ax = b$$ with a square rank deficient matrix $A$. The paper suggests to use a Moore Penrose pseudo inverse, which in my case can be computed using the ...
1
vote
1answer
517 views

name for $\underset{x}{\operatorname{argmin}} \displaystyle\sum\limits_{i=1}^n |x_i - x|$

Given a real-valued data set $ x_1, \dots, x_n $, what do you call the quantity $$\underset{x}{\operatorname{argmin}} \displaystyle\sum\limits_{i=1}^n |x_i - x|$$ This seems like a pretty basic ...
2
votes
0answers
445 views

Classical Multidimensional Scaling

Hi, I am doing an MDS with a distance matrix coming from geodesic distances between points X on a 3d mesh (ie., not euclidean distances), and try to find points Y in euclidean space which best ...
3
votes
2answers
18k views

Correlation between 3 variables

For correlation measurement betweeen 2 variables, I use Pearson formula. What formula can use to find degree of correlation between 3 variables ? My variabes are not symmetric: The correlation in ...
0
votes
1answer
178 views

Data Averging method

I have a series of 2 columns called Amount & Percentage. Now the amount is incrementing with no linear value eg 1659,3167,4495 and I want to have a data for every 1000 that is ...
1
vote
2answers
235 views

Clustering sets of sparse vectors with high dimensionality

I'm trying to write a simple recommendation system. I have a set of products that exist in a set of categories and I know whether a given customer liked a subset of the items. From this I can deduce ...
1
vote
0answers
398 views

Cluster-preserving and distance-maximizing embedding into Hamming Space?

I have a set of data, each instance in the real $[0,1]^{d}$. However, it's actually all in a relatively small range around 0.5, clustered into classes in even smaller ranges. The actual origin of the ...