3178 search results for "GIS"

A pathological glm() problem that doesn’t issue a warning

May 1, 2013
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A pathological glm() problem that doesn’t issue a warning

I know I have already written a lot about technicalities in logistic regression (see for example: How robust is logistic regression? and Newton-Raphson can compute an average). But I just ran into a simple case where R‘s glm() implementation of logistic regression seems to fail without issuing a warning message. Yes the data is a Related posts:

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Integrating Documentation and Calculation

April 30, 2013
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Integrating Documentation and Calculation Integrating Documentation and Calculation This post is a first in that I've authored it using RStudio. I would guess most people who work in computational finance or quantitative risk are at least familiar with R. Unfortunately R as...

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SAS Big Data Analytics Benchmark (Part One)

April 30, 2013
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by Thomas Dinsmore On April 26, SAS published on its website an undated Technical Paper entitled Big Data Analytics: Benchmarking SAS, R and Mahout. In the paper, the authors (Allison J. Ames, Ralph Abbey and Wayne Thompson) describe a recent project to compare model quality, product completeness and ease of use for two SAS products together with open source...

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A Brief Tour of the Trees and Forests

April 29, 2013
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A Brief Tour of the Trees and Forests

Tree methods such as CART (classification and regression trees) can be used as alternatives to logistic regression. It is a way that can be used to show the probability of being in any hierarchical group. The following is a compilation of many of the key R packages that cover trees and forests.  The goal here

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Poor man’s integration – a simulated visualization approach

April 29, 2013
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Poor man’s integration – a simulated visualization approach

Every once in a while I encounter a problem that requires the use of calculus. This can be quite bothersome since my brain has refused over the years to retain any useful information related to calculus. Most of my formal training in the dark arts was completed in high school and has not been covered

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Webinar May 1: What’s new in Revolution R Enterprise 6.2

April 29, 2013
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Revolution R Enterprise 6.2 is now available, and includes many new features that enhance the performance, scalability and enterprise readiness of R. On May 1, product manager Thomas Dinsmore will give an overview of the new features in a 30-minute webinar. You can register for the webinar (and the post-webinar slides and replay) at the link below. Revolution Analytics...

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Editing/Adding factor levels in R

April 29, 2013
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I was trying to change few levels in my factor variable by simply coercing characters on that factor variable but it dint seem to work. data(iris)iris$Species <- rep("Random", 71) ## Warning: invalid factor level, NAs generated iris$Species ## setosa ...

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Citation Patterns in Ecology

April 29, 2013
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Citation Patterns in Ecology

I’m always curious to see who is citing my one paper. Turns out I actually have two papers, and the most cited paper (with 19 citations, which sounds paltry but for me is quite exciting) is certainly not the one … Continue reading →

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How to change the alpha value of colours in R

April 29, 2013
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How to change the alpha value of colours in R

Often I like to reduce the alpha value (level of transparency) of colours to identify patterns of over-plotting when displaying lots of data points with R. So, here is a tiny function that allows me to add an alpha value to a given vector of colours, e.g. a RColorBrewer palette, using col2rgb and rgb, which has...

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Funky music in funky months: Does my taste of music change over the year?

April 28, 2013
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Funky music in funky months: Does my taste of music change over the year?

I already introduced some stuff I did with the last.fm API. But did you ever wonder if your taste of music changes over the year? Sunny music in the sunny months and dark music in darker months? Well, I did. And I want to check it out with the RLastFM ...

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