The tag has no usage guidance.

learn more… | top users | synonyms

0
votes
0answers
9 views

Trust/Distrust Dataset [on hold]

Can anybody help me, how can I find a dataset as like as Epinions which contains both Trust/Distrust feedback from users? For example in Instagram, following relation may be as trust and block ...
0
votes
0answers
23 views

Could the non-separable data become more separable by using any method of feature selection, extraction or transfomatio, or it's just a waste of time?

Could these meteorological dataset (in the figure below) be separable by any means of feature extraction, transformation, or it would be just a waste of time to make the three classes separable if ...
1
vote
0answers
37 views

Where to go next with clustered C Elegans neuronal activity series [closed]

I'm doing some independent research with the C Elegans nervous system (with the OpenWorm project) and was looking for some guidance as to where I should go next. Right now, I'm dealing with calcium ...
0
votes
0answers
15 views

fitcdiscr in octave

GNU Octave doesn't appear to have a direct equivalent to Matlab fitcdiscr. Is it under a different name or is there some similar functionality?
1
vote
1answer
78 views

FFT (Numerical Recipes in FORTRAN 77)

I am trying to use the subroutine twofft which in turn uses subroutine four1 in the book(Numerical Recipes in Fortran) to ...
3
votes
0answers
34 views

Is resampling more accurate than block average for statistical analysis of data?

I'm working in laboratories where molecular dynamics data are almost always analysed usign block average as stated in the famous Allen and Tildesley book. We divide the datas in blocks of size $M$ on ...
3
votes
1answer
105 views

Similarity of two CSV files (or more?)

A CSV file is characterized by a header, describing the n datarows to come. The header is a text string separated by a separator. A CSV header might look like (C1) ...
0
votes
0answers
21 views

How to cluster words using Jensen-Shannon Divergence?

I'm working on a project that requires text analyzing. I'm currently trying to extract keywords from a single document. I referred to this thesis(Keyword Extraction from a Single Document using Word ...
1
vote
1answer
55 views

library for arithmetic operations on unstructured xyz

I've got several sets of xyz-data where x,y are coordinates and z is a 'value'. I want to be able to do simple arithmetic operations on these data. The x,y locations are not necessarily the same in ...
1
vote
1answer
120 views

what is the best theory/model to use for prediction in multivariate data?

I use software for pollutant propagation on rivers that takes as input a set of parameters (p1, p2, ...pn) and creates an output file which is basically a matrix where on each row the concentration of ...
1
vote
1answer
43 views

Finite difference for Lighthill source term

I have experimental data containing horizontal and vertical components of speed and I need to evaluate this: $$ \frac{\partial^2}{\partial x_i \partial x_j}\left(v_iv_j\right) $$ Denoting $U$ as ...
2
votes
1answer
55 views

Is there a relationship between the covariance matrix and the partial derivative?

Suppose that there are $N$ pieces of data, each of which contains $M$ parameter values such that $N >> M$. If we put this information into matrix form ($N$ rows, $M$ columns) and then compute ...
0
votes
0answers
25 views

Meta-analysis of public 16S data - help!

I am trying to start a meta-analysis for which I want to extract some 16S-based information from public databases. Moreover, I want to relate this information with any metadata found in the associated ...
0
votes
0answers
24 views

Fuzzy Logic in Matlab with missing values

In my data set for a particular observation there are data on 5 variables say A,B,C,D,E. I use Hamacher product by taking two variables at a time. That is I combine variables A and B and ...
2
votes
0answers
36 views

similarity/distance measurement between two ranked sequence

Is there an efficient way to measure similarity/distance between two sequences of ranked numbers/letters. The two sequences are of different length, and only have some elements in common? For ...
1
vote
0answers
41 views

Manipulating/Extracting Data and Developing Methods - Language Choice [closed]

As a general programming enthusiast and aspiring Bioinformatician student I have an intermediate understanding of computing (languages) as well as Java, and to a lesser extent C++. Having knowledge in ...
5
votes
1answer
145 views

Iterative Cunnigham correction in Millikans oil-drop experiment

I tried to write an analysis program in python for the Millikan experiment based on a paper from Jones "The Millikan oil‐drop experiment: Making it worthwhile" However, I cannot reproduce the ...
0
votes
1answer
193 views

Power series regression linear fit in VBA excel

I wrote a program that calculates the best fit in VBA excel for the following model $$ y_k=c_1x_k+c_0+c_{-1}(x_k)^{-1} $$ solving for the best fit parameters $c_1$, $c_0$, and $c_{-1}$. However I ...
2
votes
1answer
39 views

Simple Path to Route Algorithm

I'm currently conducting research into subway paths, but stand in front of a problem, with no programming knowledge and an extremely short time-limit. Probably the question I am asking is trivial, ...
0
votes
0answers
28 views

What are outlier detection measures which can be used as a part of an optimization problem?

I have an optimization problem. I have to optimize some coefficient in the problem based on non-outlyingness. I need some measure of non-outlyingness which changes with respect to current classifier. ...
0
votes
1answer
54 views

Can Box-Cox transformation be applied for data of this form?

I have data of the form: X Y 3.53 0 4.93 50 5.53 60 6.21 70 7.37 80 9.98 90 16.56 100 And I want to find out $n$ so that this can be ...
0
votes
1answer
231 views

Gonzalez algorithm

I'm getting confused about implementing the Gonzalez algorithm for k-center clustering. The algorithm is : let $S$ be a data set Choose $z_1 \in S$ arbitrarily. Number $z$ is center. (In general ...
1
vote
0answers
19 views

Concatenating small windows of EEG signals over trial

My question is regarding the mathematical implications of concatenating very small windows from different trials, of the same size and for the same period in time after a stimuli. In other words, ...
0
votes
0answers
38 views

spline derivation

Assume the following representation for cubic splines with $T$ interior knots is given. Let $g(Y)=\sum_{j=0}^3 \alpha_j Y_j+\sum_{t=1}^T \gamma_t (Y-\zeta_t)_{+}^{3}$ where $(Y-\zeta_t)_{+}:= ...
0
votes
2answers
113 views

What is 'SOLVER' in R and Statistics/Analytics ?

**strong text**a) I tried to research on what exactly is a SOLVER only to find a not clear-cut simple answer. My doubts still remain after going through several sites full of discussions about it. I ...
5
votes
2answers
244 views

Dimensionality reduction of the domain of f(x)

I'm wondering if there is something analogous to a PCA for data sets where there is a dependent variable. (Though I am interested in any method of dimensionality reduction, PCA is just an example.) ...
3
votes
1answer
106 views

Monte Carlo Simulation - Random Number Motivation

For Monte Carlo simulations, or any other numerical methods that rely heavily on the quality of the pseudo-random numbers generated (i.e even/desired distribution on a certain domain) for that matter, ...
7
votes
4answers
272 views

Should I use a database to handle large amounts of results?

Background: I am currently running a large amount parameter variation experiments. They are being run in Python 2.6+, using numpy. These experiments are going to take about 2 weeks to run. Roughly I ...
1
vote
0answers
120 views

SciDB vs OLAP cube

I am working on good retrieval mechanism for big data systems. I am of view that multidimensional structures could be of great use for aggregations and querying . Multidimensional structures as ...
2
votes
2answers
130 views

Extracting time scales information from empirical cumulative distribution function

I have a stochastic process (a Markov chain actually) that has two absorbing states. I am using a difference equation to calculate the first passage time to either of the absorbing states. There are ...
0
votes
1answer
54 views

Finding maximum value in huge dataset

I am working on a project involving some pattern recognition. For this I need to find the maximum value in a huge multidimensional dataset. For example I have a discrete 5-dimensional space containing ...
2
votes
0answers
82 views

Spatio-temopral wavelet analysis

Am quite new to wavelet analysis and would like some help. I am performing a spatio-temporal analysis of monthly gridded rainfall data. With PCA, I can reduce the dimension of the rainfall data into a ...
8
votes
2answers
2k views

Pandas limitations and its alternatives in Python

I read somewhere that Pandas was first developed for the financial world, at least not especially for natural sciences (physics, biology and so on), so is there any similar data analysis Python ...
2
votes
3answers
214 views

R/C/C++ library for N-dimensional arrays

I'm looking for a library that is either in R or easily wrappable with R, that can do the following things: construct and subset N-dimensional arrays perform operations such as ...
5
votes
1answer
393 views

Fit my data to Lissajous curve in Matlab

I'm acquiring data which looks like this: Theoretically it should be possible to fit it with a Lissajous curve, which is typically defined in the following way: $x = A \sin(a t + \delta)$, and $y = ...
1
vote
1answer
48 views

Line scan in a 2D histogram

So I have a 2D histogram, in the third dimention are the counts. What I want to achieve is by choosing two random position, make a plot of a 1D histogram along the line that passes through the two ...
1
vote
0answers
36 views

Spectra of the energy flux VS transfer spectra?

In direct numerical simulation of turbulence what is the advantage to look at the spectra of the energy flux rather than the transfer spectra? The transfer spectra corresponds to the triple-velocity ...
1
vote
1answer
34 views

Adding data with different abscissas

This question may be better suited for an Astronomy Stack Exchange site, but I figured I'd ask here. Say I have measurements of something as a function of radius for a number of objects. Here's an ...
3
votes
2answers
58 views

Parameter Fitting: Need measure of data 'support' for a parameter solution

I am estimating parameters on a dataset that would, for the most part, result in a weakly constrained solution. The dataset however also contains a few more data points that make the solution ...
1
vote
1answer
60 views

Extract clusters from a graph of absolute-distance edge

I don't know if I have formulated this problem right: I have tons of items and the distances between each pair of them. Feeding this data into some visualization tool, I am able to create a nice ...
2
votes
0answers
53 views

Error in treating non-uniformly spaced data as uniform

In discussing smoothing filters, Numerical Recipes p. 772 says ... irregularly sampled data, where the values $f_i$ are not uniformly spaced ... one can simply pretend that the data points are ...
3
votes
1answer
507 views

How to do local FFT on huge 3D vector data cell mesh and visualize it spatially?

Simulation type: I'm running a simulation with the OOMMF micromagnetics package http://math.nist.gov/oommf/ where are magnet is represented by a mesh of 3 million cells, it gets excited by a ...
1
vote
1answer
97 views

classification machinery needed

Consider a set of 7D vectors. Each vector belongs to one of four classes. After mapping to 3D with PCA and coloring each point according its class the dataset looks like as shown below: For the ...
1
vote
1answer
213 views

Clustering data based on the radius of a sphere

I have a data-set that has four columns [X Y Z C]. I would like to find all the C values that are in a given sphere centered at [X, Y, Z] with a radius r. What is the best approach to address this ...
5
votes
1answer
237 views

Recommendation for a python book for data processing

I've been doing FORTRAN programming for 10 years and I've started using python for a few years now, mostly for data processing. I've been lucky enough to work with people that are knowledgeable ...
1
vote
2answers
72 views

Estimate (non-)drift in noisy data

I have a time series representing the result of a complex calculation (physical simulation). Due to round-off errors and approximation errors, there will be some "noise" on the data series. In some ...
9
votes
4answers
6k views

Fastest PCA algorithm for high-dimensional data

I would like to perform a PCA on a dataset composed of approximately 40 000 samples, each sample displaying about 10 000 features. Using Matlab princomp function consistently takes over half an hour ...
3
votes
1answer
106 views

Calculation of Multivariate Coherence

I trying to detecting whether a data set of time series has a global change in frequencies. Calculating the average (or median) pairwise coherence, I feel, misses the point because I am trying to get ...
2
votes
0answers
962 views

Can post-processing use topoSet and createPatch without screwing up the results?

I would like to use patchAverage to obtain the average pressure on an object that consists of multiple patches (due to different boundary conditions), however ...
9
votes
2answers
587 views

Best practice for storing hierarchical simulation data

TL,DR What is the accepted best practice in scientific computing circles for storing large quantities of hierarchically structured data? For example, SQL does not play nicely with large sparse ...