# Monthly Archives: July 2013

## change in weight of cars plot

July 7, 2013
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Based on last week's faster algorithm I wanted to finish with car weights. Unfortunately a fail again. By now it is a fail of myself, it needs a bit more dedication and grunt than I am willing and able to give for this blog. This week I added...

## Interactive Heatmaps (and Dendrograms) – A Shiny App

July 7, 2013
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Heatmaps are a great way to visualize data matrices. Heatmap color and organization can be used to  encode information about the data and metadata to help learn about the data at hand. An example of this could be looking at the raw data  or hierarchically clustering samples and variables based on their similarity or differences.

## rgeos: TopologyException – found non-noded intersection between..

July 7, 2013
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I have been having some issues generating spatial unions and intersections using the rgeos package. The package is extremely powerful, as it serves as an R interface to the powerful GEOS engine. However, when working with shapefiles or polygons, quite often you will come across a whole range of errors, typically around topology exceptions. These occur

## ggmap : Interesting toolbox for spatial analysis

July 7, 2013
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ggmap is a new tool which enables such visualization by combining the spatial information of static maps from Google Maps, OpenStreetMap, Stamen Maps or CloudMade Maps with the layered grammar of graphics implementation of ggplot2The library is developped by David Kahle and Hadley Wickham and in the latest R/Journal (Volume 5/1, June 2013),...

## RFM Customer Analysis with R Language

July 7, 2013
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For database marketing or direct marketing people, they are always concerned about two questions before they send out mails or make calls to their customers:- How can they segment the customers in the database to find out who are more likely to response to their mails or buy their products? Which type of customers they

## Variance Swap Replication in R.

July 6, 2013
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As I was studying volatility derivatives I made some charts that represent some key features of replication. Say variance swap has a payoff function $$f=(\sigma - K_{VOL})$$, which means that $$K_{VOL}$$ will most likely be the forward volatility clos...

## Variance Swap Replcation in R.

July 6, 2013
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As I was studying volatility derivatives I made some charts that represent some key features of replication. Say variance swap has a payoff function $$f=(\sigma^2 - K_{VOL})$$, which means that $$K_{VOL}$$ will most likely be the forward volatility cl...

## Getting raster histogram in QGIS using SEXTANTE and R

July 6, 2013
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The issue with the broken histogram creation tool in QGIS annoyed me far too long. Sometimes you just need a quick glance on the histogram of a raster just to make a decision on how to process it or just to assess distribution of classes. But as you kn...

## A Recipe for Trellis/Faceted Plots Using Base R Graphics

July 5, 2013
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I frequently use lattice and ggplot2 to create trellis/faceted graphics. But, I gave up using these packages in a recent application, where I had initially constructed a complex graphic using the base R plotting functions. When I later decided that I wanted a faceted version, there was a dilema: re-create the complex graphic using lattice

## Veterinary Epidemiologic Research: Modelling Survival Data – Parametric and Frailty Models

July 5, 2013
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$Veterinary Epidemiologic Research: Modelling Survival Data – Parametric and Frailty Models$

Last post on modelling survival data from Veterinary Epidemiologic Research: parametric analyses. The Cox proportional hazards model described in the last post make no assumption about the shape of the baseline hazard, which is an advantage if you have no idea about what that shape might be. With a parametric survival model, the survival time