846 search results for "maps"

Returns with negative net asset values

July 30, 2012
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Returns with negative net asset values

How are returns calculated when net asset value goes negative? Previously In “A tale of two returns” we highlighted the similarities and differences of log returns versus simple returns. Positive valuation We create — in R — an example of net asset value at four times: > nav1 <- c(1000, 900, 950, 1010) > nav1 … Continue reading...

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Petrol prices adjusted for inflation

July 28, 2012
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Petrol prices adjusted for inflation

Petrol prices adjusted for inflation (Perth, Western Australia) The thought for this sprung to mind when I saw petrol drop below $1.20 per litre the other day, and it made me think, I remember paying that when I got to … Continue reading →

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Getting rasters into shape from R

July 25, 2012
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Getting rasters into shape from R

Today I needed to convert a raster to a polygon shapefile for further processing and plotting in R. I like to keep my code together so I can easily keep track of what I’ve done, so it made sense to … Continue reading →

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Learning R has really made me appreciate SAS

July 25, 2012
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For the past 18 months, it seems like all I’ve heard about in the digital marketing industry is “big data”, and with that, mentions of using Hadoop and R to solve these sorts of problems.  Why are these tools the … Continue reading →Learning R has really made me appreciate SAS is an article from randyzwitch.com,...

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Modeling Trick: Impact Coding of Categorical Variables with Many Levels

July 23, 2012
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Modeling Trick: Impact Coding of Categorical Variables with Many Levels

One of the shortcomings of regression (both linear and logistic) is that it doesn’t handle categorical variables with a very large number of possible values (for example, postal codes). You can get around this, of course, by going to another modeling technique, such as Naive Bayes; however, you lose some of the advantages of regression Related posts:

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Map biodiversity records with rgbif and ggmap packages in R

July 23, 2012
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Map biodiversity records with rgbif and ggmap packages in R

When I attended usrR! 2012 last month, there was an interesting presentation by Dr. David Kahle about the package ggmap. It is a package built over ggmap2 and helps us map spatial data over online maps like Google maps or Open Street Maps. I decided to give ggmap package a try with biodiversity data. So

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Map biodiversity records with rgbif and ggmap packages in R

July 23, 2012
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Map biodiversity records with rgbif and ggmap packages in R

When I attended usrR! 2012 last month, there was an interesting presentation by Dr. David Kahle about the package ggmap. It is a package built over ggmap2 and helps us map spatial data over online maps like Google maps or Open Street Maps. I decided to give ggmap package a try with biodiversity data. So

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Health Care Costs – Part 3, "Why You Are Paying More"

July 19, 2012
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Health Care Costs – Part 3, "Why You Are Paying More"

Malpractice - A Booming Industry? Perhaps authors Frank Sloan, Randall Bovbjerg and Penny Githens capture it best from their book Insuring Medical Malpractice: "If aging Doctor Kildare were to return to medical practice today, having been...

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Mapping Public Opinion: A Tutorial

July 18, 2012
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Mapping Public Opinion: A Tutorial

At the upcoming 2012 summer meeting of the Society of Political Methodology, I will be presenting a poster on Isarithmic Maps of Public Opinion. Since last posting on the topic, I have made major improvements to the code and robustness of the modeling approach, and written a tutorial that illustrates the production of such maps. This … Continue reading →

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Project Euler — problem 14

July 16, 2012
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Project Euler — problem 14

It’s Monday today! It’s work day! And I’ve already worked on computer for two hours. Time for a break, which is the 14th problem of Project Euler. The following iterative sequence is defined for the set of positive integers: n n/2 (n … Continue reading →

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