# 2702 search results for "GIS"

## Pseudo-Random vs. Random Numbers in R

November 25, 2011
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Happy Thanksgiving, everyone. Earlier today, I found an interesting post from Bo Allen on pseudo-random vs random numbers, where the author uses a simple bitmap (heat map) to show that the rand function in PHP has a systematic pattern and compares these to truly random numbers obtained from random.org. The post’s results suggest that pseudo-randomness in PHP is

## If you are writing a book on Bayesian statistics

November 23, 2011
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This post is somewhat marginal to R in that there are several statistical systems that could be used to tackle the problem. Bayesian statistics is one of those topics that I would like to understand better, much better, in fact. … Continue reading →

## Prague Half Marathon Ranking: 2% or 25% missing?

November 23, 2011
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I am a regular participant of Prague International Half Marathon. In a mass event like this the horde of runners needs a long time to reach the starting line. To make the times mutually comparable the “start time” is measured and afterwards subtracted from the “finish time”. Also the crowd is organized to corridors in such...

## Volume by Price Charts using R

November 23, 2011
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R-Bloggers is a wonderful site which offers some great ideas for analysis.While I have been busy of late, hence could not do much with R, I was inspired by this post by Eric Nguyen on Volume by Price chart. This chart can be used with a great effe...

## Time series cross-validation 2

November 22, 2011
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In my previous post, I shared a function for parallel time-series cross-validation, based on Rob Hyndman's code.  I thought I'd expand on that example a little bit, and share some additional wrapper functions I wrote to test other forecasting&nbsp...

## Functional and Parallel time series cross-validation

November 21, 2011
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Rob Hyndman has a great post on his blog with example on how to cross-validate a time series model.  The basic concept is simple:  You start with a minimum number of observations (k), and fit a model (e.g. an arima model) to those observation...

November 17, 2011
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The most recent edition of the Revolution Newsletter is out. The news section is below, and you read the full November edition (with highlights from this blog and community events) online. You can subscribe to the Revolution Newsletter to get it monthly via email. R Training from Hadley Wickham: The R guru (and author of ggplot2, plyr and several...

## GEO2R: Web App to Analyze Gene Expression in GEO Datasets Using R

November 17, 2011
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Gene Expression Omnibus is NCBI's repository for publicly available gene expression data with thousands of datasets having over 600,000 samples with array or sequencing data. You can download data from GEO using FTP, or download and load the data direc...

## Using neural network for regression

November 17, 2011
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Artificial neural networks are commonly thought to be used just for classification because of the relationship to logistic regression: neural networks typically use a logistic activation function and output values from 0 to 1 like logistic regression. However, the worth … Continue reading →