2615 search results for "gis"

Upcoming events

October 9, 2012
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Upcoming events

Featured I’ll be leading two courses in the near future: Value-at-Risk versus Expected Shortfall 2012 October 30-31, London. 30th: “Addressing the critical challenges and issues raised by the Basel proposal to replace VaR with Expected Shortfall” 31st: “Variability in Value-at-Risk and Expected Shortfall” led by Patrick Burns Details at CFP Events. Finance with R Workshop … Continue reading...

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Two ways that correlation and stepwise regression can give different results

October 8, 2012
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In general, a correlation test is used to test the association between two variables (y and z). However, if there is a third variable (x) that might be related to z or y, it makes...

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Functions for plotting and getting Greek in labels

October 8, 2012
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Functions for plotting and getting Greek in labels

The problem: We often want to plot data and assign plot attributes based on characteristics of the data. For example, if we have a group of students with the following IQs, we might want to indicate who is an outlier in the statistical sense. I like...

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How to read BSMAP methylation ratio files into R via methylKit

October 5, 2012
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BSMAP is an aligner for bisulfite sequencing reads. It outputs aligned reads as well as methylation ratios per base (via methratio.py script). The methylation ratios can be read into R via methylKit package and regular methylKit analysis can ...

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Calculating distances (across matrices)

October 5, 2012
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Calculating distances (across matrices)

This Gist is mostly for my future self, as a reminder of how to find distances between each row in two different matrices. To create a distance matrix from a single matrix, the function dist(), from the stats package is sufficient. There are times, ho...

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Adding Measures of Central Tendency to Histograms in R

October 4, 2012
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Adding Measures of Central Tendency to Histograms in R

Building on the basic histogram with a density plot, we can add measures of central tendency (in this case, mean and median) and a legend.Like last time, we'll use the beaver data from the datasets package.hist(beaver1$temp, # histogram col =...

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Log odds ratios and an indicator matrix from categorical data

October 4, 2012
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Log odds ratios and an indicator matrix from categorical data

A long title, but there are a couple of handy things in this Gist. The first, and more obscure, is the conversion of a data.frame of categorical variables into a matrix of dummy/binary/indicator variables, one for each category of each original variab...

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Transforming a color scale

October 3, 2012
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Transforming a color scale

In developing plots, I often use color (or “colour” in ggplot2 parlance) to reflect values of a third, non-X/Y, variable. Depending on the distribution of this Z variable, however, the effective color range can be narrow, making it difficul...

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Emerging as Low Vol

October 2, 2012
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Emerging as Low Vol

Extending the series begun with When Russell 2000 is Low Vol, I thought I should take a look at Emerging Market stocks during periods of low relative volatility to the S&P 500.  So you can replicate even without access to expensive data, let

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A replacement for theme_blank()

October 2, 2012
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A replacement for theme_blank()

ggplot2 has just hit 0.9.2, and with the change comes a new theme system. Previous versions of ggplot2 offered a theme_blank(), which was a stripped-down, essentially blank plotting canvas, but it is now deprecated. github user jrnold has produced a s...

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