Blog Archives

Clipping a Surface By a Polygon

September 8, 2010
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Clipping a Surface By a Polygon

Background: A common function in standard GIS software enables users to create a raster surface and extract values or clip it based on a set of polygons. This may be used in cases where you want analysis to be constrained to within a town’s boundaries or a coastline. This tutorial will outline how to create

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Writing a Spatial Function: The Location Quotient

September 7, 2010
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Writing a Spatial Function: The Location Quotient

Background: In some cases it is necessary to conduct the same analysis multiple times on either the same or different data. In such circumstances it is worth writing a function to simplify the code. In this example the location quotient provides a simple calculation easily written in to a function. The location quotient (LQ) is

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R Maps

September 6, 2010
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R Maps

This is an updated version of my Making Maps with R tutorial. I think the code is lot simpler and it also includes some data for you to play around with. Background: Spatial data are becoming increasingly common, as are the tools available in R to process it. Of course one of the best ways

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Free GIS Resources

January 26, 2010
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Free GIS Resources

Over the last couple of days I have utilised some excellent free GIS resources. I have listed these and some others below. Geospatial Analysis: This is the free online version of de Smith, Longley and Goodchild’s excellent book by the same title. It provides full coverage of current GIS methodologies. It also provides extensive information

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Making Maps with R

January 13, 2010
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Making Maps with R

***This tutorial has been updated, please click here*** I frequently use R (a free software environment for statistical computing and graphics) for data analysis.  As almost all my data are spatial it is often good to produce a map of the results without having to export the data into another GIS package. I am often

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Lattice: Multivariate Data Visualization with R

January 11, 2010
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Lattice: Multivariate Data Visualization with R

I have just reviewed Sarkar‘s Lattice: Multivariate Data Visualization with R for the Journal of the Royal Statistical Society Series A.  I would highly recommend the book to all R users who wish to produce publication quality g...

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Applied Spatial Data Analysis with R

August 25, 2009
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Applied Spatial Data Analysis with R

I have just reviewed the book Applied Spatial Data Analysis with R which has been published in the September2009  issue of the Royal Statistical Society’s Significance magazine. Applied Spatial Data Analysis with R is an accessible text that demonstrates and explains the handling of spatial data using the R Software Platform. The text’s authors have

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