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18 views

Correlation and Dependence [on hold]

It is well known that 0 dependence implies 0 correlation, while 0 correlation does not imply 0 dependence. I have a paper here illustrating nonlinear correlation coefficients from relationship ...
3
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20 views

Pivot-friendly binning of arbitrary vector

I frequently get a situation in which I want a pretty binned column from a vector of values, so that I divide the vector in approximately even ranges and choose 'sensible' values so that it looks ...
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29 views

Algorithm for correcting missing values

I have problem with setting missing values in data frame. In the first 3 columns there are ID of product, ID of store, and number of week. There are also 28 columns from 4 to 31 corresponding to last ...
2
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1answer
62 views

Nonlinear Scaling Normalization

I have a procedure for normalizing variables, the details of which can be viewed in this white paper. I would like to be able to make the routine scalable to handle any number of variables. Below is ...
3
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2answers
55 views

Reducing memory usage for FizzBuzz in R

I've been trying all night to get my fizzbuzz to use below 20 MB of RAM but I can't seem to get it much smaller than this. ...
2
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1answer
40 views

Fast canonical indexing of elements in array

Given two arrays of elements: aaabbccdefaa zzzccddafgzz I want to check whether these two arrays are equivalent up to a relabeling. My strategy is to map them into a canonical form and ...
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72 views

Time-course of drug amounts in the different compartments of a pharmacokinetic system

I am looking for a way to speed up applying my function to every individual in the data frame. Currently I am using the ddply but it is very slow for big data sets. ...
2
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0answers
94 views

Genetic algorithm for the minimum of the Schaffer function

I have to implement a genetic algorithm in R to optimize the minimum of the Schaffer function. Below I describe each step and I need to create one big function and another loop for 100 iterations (and ...
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62 views

Stochastic gradient descent in R

Please, review my code, which counts global minimum with method stochastic gradient descent for schaffer function ...
4
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1answer
128 views

Simulated annealing in R

I am new in R and I have to implement simulated annealing for schaffer function and I did it. However I am not sure about the correctness of the code. ...
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0answers
63 views

Naive Grouping for Factorization

I have a naive grouping method for factorization. I am curious as to its novelty and aspects of the code below that will increase its efficiency. The method is best described with an example: For n ...
3
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1answer
102 views

Trial Multiplication for Factorization

I am trying a trial multiplication for factorization. This is a general example, but each sequence can be specified to pairs of sequences \${p,q}\$ for a given \$n\$. For example, if \$n\$ ended in 3, ...
3
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37 views

Computing pairwise distance covariances for a symmetric matrix

I wrote a non-vectorized, non-parallel wrapper function for computing the pairwise distance covariances (Wikipedia) (original paper) in a data frame: ...
6
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2answers
55 views

2D lattice random walk plots in functional style

To practice writing code in the functional programming style, I wrote a program to plot two-dimensional lattice random walks. I'd appreciate any feedback about how to improve its "functionaliness". ...
4
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59 views

Crawling and parsing meteorological data from the web into R

I am interested in collecting directly into R data published by the Mexican Met-office. The data pieces are spread through several URLs, but one can start here. There I can get the names and ...
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58 views

Extract and rename specific columns of a CSV data file

I have a CSV data file with 3,896 columns (variables), and I am attempting to extract a particular subset of columns for use in a data analysis project. To avoid the burden of having to constantly ...
6
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1answer
58 views

Lookup GINI by year and country

This takes a dataframe as an argument, looks at all pairs of two columns in that data frame (country and year) and returns a column value of that pair in another data frame (the gini number). ...
4
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1answer
142 views

Sublime Text 2 R Build System (source file, send selection to interactive session)

The following is the description of the R build system I am using (very happy) with Sublime Text 2 on linux (Crunchbang). With it, I am able to: to source the current file.R to an interactive R ...
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0answers
93 views

Smoothing matrix for visual representation

I recently started playing around with R and am currently trying to plot GPS data points onto a perspective plot. I have a script that works and I get my desired results out of it and it works ok for ...
3
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0answers
39 views

Volatility updating with Heston-Nandi model

I'm trying to program a volatility updating rule using iteration. I start with the well-known Heston-Nandi model where the returns dynamics are: $$ \left\{ \begin{array}{rcl} R_{t+1} ...
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1answer
105 views

Quick estimation for empirical permutation and correlation test in R

I have two matrices (a, b), each including 3 genes and 6 observations. I have estimated the Spearman correlation for gene pairs (rcorr.observed). Then I want to do an empirical permutation (1000 ...
3
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2answers
67 views

Python path-breaking script for use in R

R does not support line continuation as Python, and it's disturbing to have long file paths like /media/user/data/something-not-very-important-but-super-long/some-curious-secret-file.pdf and ...
4
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1answer
52 views

Creating a special Toeplitz matrix in R

I'd like to know if there is a standard way of creating a matrix like the one shown below using the R programming language. $$ \begin{bmatrix} 1 & \rho & \rho^2 & \cdots ...
4
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2answers
101 views

Concisely adding values in a loop to a column

In my data frame I assign values to the column Register by checking another column (Source) for specific values. Based on those values, the output in Register changes. I am relatively new to R, but I ...
3
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1answer
57 views

Simulation of animal skins

This is a simulation of animal skins, like a cellular automat. I'd like it improved. ...
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0answers
28 views

Comparison of two regression types on the same set of models

I wrote a relatively simple R script to run a bunch of regressions. To be precise, it is a hurdle negative binomial regression (fancy stuff for count data). To print it out easily to ...
3
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1answer
32 views

Merging predicted values into measured values

I created the following function below to merge the real values with the predicted values (when real are absent) in a new column in data.frame. The function ...
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3answers
131 views

An R function for checking whether a variable is binary or continuous

This function takes a numeric vector and returns "con" if it's continous and "bin" if it's binary. It does not take the multinomial case into account, i.e. if a variable y has three possible values ...
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1answer
74 views

Speeding up nested for-loop analysis code

I have two matrices, the first one is mat 2000*500, the second one is 6000*500 ...
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1answer
49 views

Frequency form to case form - unexpected values in table

I'm taking count data on voting preferences by race and entering it into a table in frequency form, then expanding out to case form and using CrossTable to look at ...
3
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65 views

Finding the Cox regression coefficients in a mixed model for microarray data

I have written a code for a project which aims at finding the Cox regression coefficients in a mixed model for microarray data. The study was carried out on the Affymetrix Hgu133a platform. In the ...
5
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1answer
100 views

Vector comparison inside for-loop

The following code finds no-rain periods in a time series that were preceded by rain over a threshold (e.g. 10mm in 2 days [k=48]). ...
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2answers
179 views

Plot daily time spent on codereview.stackexchange.com

This draws an xyplot from csv data obtained from RescueTime API for activity time for "http://codereview.stackexchange.com". ...
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1answer
54 views

How I can generalise this code

I have this code and I want to generalize it and make it efficient. Each time I generate a number of random variables and I put it in the m equation to generate m. Can I get any help to simplify this ...
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0answers
29 views

Computing values with several large numeric vectors

I have several large numeric vectors (close to 1e6 entries each) and I need to make some computations with their values: ...
5
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1answer
204 views

Using Reddit API in R

I'm scraping some comments from Reddit using Reddit JSON API and R. Since the data does not have a flat structure, extracting it is a little tricky, but I've found a way. To give you a flavour of ...
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2answers
144 views

Calculation of mortgage repayments

I've just started learning R, but I feel that I'm using it only as a normal procedural language without taking advantage of some built-in functions and data structures. I wrote a function that ...
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70 views

Vectorize Fisher's Exact Test

I have two data frames/ lists of data, humanSplit and ratSplit, and they are of the form ...
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1answer
227 views

Generating Cartesian product of strings in R

Sometimes I need to create character vectors like this one: ...
5
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1answer
284 views

Mean of many subsets of a dataframe

I have large dataframe containing many replicates. The replicates are in groups of 3. So the first 3 replicates are in column 1, 2 and 3. The second set 4, 5 and 6... and so on. Now I create a new ...
2
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1answer
72 views

Data model code running too slowly

The model takes a long time to run. I have tried to vectorise it as far as I can, but it's still taking about a day to compute. I'm wondering if it's possible to speed it up. Maybe the problem isn't ...
6
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1answer
170 views

Merging overlapping/intersecting string vectors

I am trying to merge overlapping/intersecting sets given as a list of string vectors below in R (my actual data set has thousands of such sets). The overlap/intersection is based on the ...
3
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1answer
109 views

Calculating overlap of segments in chromosome data

I wrote an R code that basically performs 2 operations: For each segment in file A, find all segments in file B that lie in that segment. Find the percentage of overlap for each case in previous ...
2
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0answers
42 views

Speed up my backward model selection

I have implemented a quite long program in R and I have noticed that one block, concearning a backward model selection, is too slow and I would like to receive some suggestions in order to speed up ...
4
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2answers
68 views

Imperative code in R keeping track of state

A friend of mine has a spreadsheet where she coded a classroom video for various teaching events, which I needed to help her plot. For each recording, she used several video cassettes, and her time ...
3
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1answer
418 views

Replace for loop while with apply family function in R

I have trouble with for loop, my code runs very slowly. The thing I want to do is to use function from apply family to make my codes run faster (instead of using ...
2
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0answers
43 views

Merton default model with complex iterative approach

I am using Merton default model with complex iterative approach. I have already prepared my R codes but as I am quite new in R, they seem very inefficient, in sense that they runs almost 7 hours. My ...
2
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1answer
128 views

Backwards stepwise regression code in R (using cross-validation as criteria)

I want to write code that does backward stepwise selection using cross-validation as a criterion. I have only started learning R a month ago and I have almost zero programming experience prior to ...
0
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2answers
212 views

Optimizing the function in R by replacing for loop

I am trying to create a function that I want to use in my real data. Is there any way to optimize the following function? This is a function I created to filter the data. ...
3
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1answer
1k views

best way to apply across an xts object

As xts objects are arrays, getting apply functions to work is a little tricky if you want to preserve the dates. For example, take the ...