2738 search results for "gis"

Mapping Bike Accidents in R

September 14, 2012
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Mapping Bike Accidents in R

At last weekend’s Hack Ta Ville event here in Montreal, I joined up with some talented urban planners and web devs to realize Vélobstacles. The idea of the project is to crowd source information on cycling conditions around the city. As with any crowd sourcing project, we were faced with the problem of seeding the

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OO in R

September 13, 2012
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OO in R

"Is there a package for obfuscating code in #rstats?", someone asked. "The S4 object system?!" came the snarky reply. If you're smiling right now, you know that it wouldn't be funny if it weren't at least a little bit true. Options: S3, S4 or R5? There can be little doubt that object oriented...

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A function to find the “Penultimax”

September 13, 2012
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A function to find the “Penultimax”

Penulti-what?  Let me explain: Today I had to iteratively go through each row of a donor history dataset and compare a donor’s maximum yearly donation total to the second highest yearly donation total.  In even more concrete terms, for each … Continue reading →

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Word Clouds in R

September 13, 2012
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Word Clouds in R

Thanks to the wordcloud package, it's super easy to make a word cloud or tag cloud in R.In this case, the words have been counted already. If you are starting with plain text, you can use the text mining package tm to obtain the counts. Other blog...

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Second Milano R net meeting

September 11, 2012
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Second Milano R net meeting

September 27, 2012 - 18:00 - 21:00 Fiori Oscuri Bistrot & Bar (www.fiorioscuri.it) Via Fiori Oscuri, 3 - Milano (Zona Brera) Continue reading →

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Item Response Theory: Developing Your Intuition

September 10, 2012
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Item Response Theory: Developing Your Intuition

Suppose that you accepted my argument from the last two posts on halo effects and bifactor models.  As you might recall, I argued that when respondents complete rating scales, they predominating rely on their generalized impression with a more minor role played by the specific features that the ratings were written to measure.  Consequently, we...

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Violence along Mexico’s Southern Border and Central America

September 7, 2012
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Violence along Mexico’s Southern Border and Central America

Rates for Panama and Nicaragua are from 2009, all other countries 2010. Municipalities which are part of a metro area in Mexico are shown with the metro area homicide rate.Visit the interactive map of homicides Having just posted on violence along Mexico's northern border, I figured it's time to...

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Big Issue with System Backtests

September 7, 2012
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Big Issue with System Backtests

Almost always, when I see a system backtested, the backtest assumes a static portfolio with no contributions or withdrawals.  This assumption only covers an extremely limited subset of my clients.  Cash flows in and out of a portfolio or syst...

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More on fixed and random effects: Plotting and interpreting

September 7, 2012
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More on fixed and random effects: Plotting and interpreting

In a recent post I showed how plotting model fits can help to interpret higher-order polynomial terms. The key comparison there was between a model that did and did not have the higher order fixed effect terms. If you're going to use this strategy, you need to...

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Coming up: Two weeks of awesome guest bloggers

September 7, 2012
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I'm heading out on vacation to my Australian homeland for the next two weeks, but fear not reader friends: we have an awesome lineup of guest bloggers to fill in while I'm away. I don't want to ruin the surprise, but you'll be seeing posts from: experts in data visualization about how they use R; members of the R...

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