3177 search results for "GIS"

Parallel Processing: When does it worth?

May 29, 2013
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Parallel Processing: When does it worth?

Most computers nowadays have few cores that incredibly help us with our daily computing duties. However, when statistical softwares do use parallelization for analyzing data faster? R, my preferred analytical package, does not take too much advantage of multicore processing by default. In fact, R has been inherently a “single-processor” package until nowadays. Stata, another

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Intended or Unintended Consequences

May 28, 2013
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Intended or Unintended Consequences

(This article was first published on Timely Portfolio, and kindly contributed to R-bloggers) A quick glimpse at the US 10y Treasury Bond rate since 2000 seems benign with low volatility and a general downward trend. require(latticeExtra)require(quantmod)US10y <- getSymbols("^TNX", from = "2000-01-01", auto.assign = FALSE)asTheEconomist(xyplot(US10y, scales = list(y = list(rot = 1)), main = "US 10y Yield Since 2000"))...

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Using R to communicate via a socket connection

May 28, 2013
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Occasionally, the need arises to communicate with R via another process. There are packages available to facilitate this communication, but for simple problems, a socket connection may be the answer. Nearly all software languages have a socket communic...

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Writing a Minimal Working Example (MWE) in R

May 27, 2013
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Writing a Minimal Working Example (MWE) in R

How to Ask for Help using R How to Ask for Help using R The key to getting good help with an R problem is to provide a minimally working reproducible example (MWRE). Making an MWRE is really easy with R, and it will help ensure that...

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Bayesian model II regression

May 27, 2013
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Bayesian model II regression

Regression is a mainstay of ecological and evolutionary data analysis. For example, a disease ecologist may use body size (e.g. a weight from a scale with measurement error) to predict infection. Classical linear regression assumes no error in covariates; they are known exactly. This is rarely the case in ecology, and ignoring error in covariates can bias regression coefficient...

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(Another) introduction to R

May 27, 2013
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(Another) introduction to R

It’s Memorial Day and my dissertation defense is tomorrow. This week I’m phoning in my blog. I had the opportunity to teach a short course last week that was part of a larger workshop focused on ecosystem restoration. A fellow grad student and I taught a session on Excel and R for basic data analysis.

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Log Transformations for Skewed and Wide Distributions

May 27, 2013
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Log Transformations for Skewed and Wide Distributions

This is a guest article by Nina Zumel and John Mount, authors of the new book Practical Data Science with R. For readers of this blog, there is a 50% discount off the “Practical Data Science with R” book, simply by using the code pdswrblo when reaching checkout (until …Read more »

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Combinatorial optimization with gaoptim package

May 27, 2013
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My recent update of gaoptim package brings up a new function, GAPerm, which can be used to perform combinatorial optimization using the Genetic Algorithm approach. The example below solves a TSP instance with 10 points around a circumference, the...

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Import All Text Files in A Folder with Parallel Execution

May 26, 2013
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Import All Text Files in A Folder with Parallel Execution

Sometimes, we might need to import all files, e.g. *.txt, with the same data layout in a folder without knowing each file name and then combine all pieces together. With the old method, we can use lapply() and do.call() functions to accomplish the task. However, when there are a large number of such files and

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Using R to visualize geo optimization algorithms

May 26, 2013
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Using R to visualize geo optimization algorithms

Site optimization is the process of finding an optimal location for a plant or a warehouse to minimize transportation costs and duration. A simple model only consists of one good and no restrictions regarding transportation capacities or delivery time. The optimizing algorithms are often hard to understand. Fortunately, R is a great tool to make them more comprehensible.The basic...

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