2810 search results for "gis"

Load PostGIS geometries in R without rgdal

January 14, 2014
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As I said in my last post, rgdal lacks some of the features of GDAL, including the ability to subset columns and rows the source layer, and I demonstrated a workaround. The workaround relied upon the RPostgreSQL package, and this raises a question: Is it possible to transfer geographic data from PostGIS to R just

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An R package with all injury intent deaths registered in Mexico 2004-2012

December 17, 2013
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This is a data only package containing all injury intent deaths (accidents, suicides, homicides, legal interventions, and deaths of unspecified intent) registered by the SSA/INEGI from 2004 to 2012. The data source for the database is the INEGI. In a...

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Logistic Regression with R: step by step implementation part-2

December 8, 2013
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Logistic Regression with R: step by step implementation part-2

Welcome to the second part of series blog posts! In previous part, we discussed on the concept of the logistic regression and its mathematical formulation. Now, we will apply that learning here and try to implement step by step in R. (If you know concept of logistic regression then move ahead in this part, otherwise The post Logistic...

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Logistic Regression with R: step by step implementation part-1

November 30, 2013
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Logistic Regression with R: step by step implementation part-1

Very warm welcome to first part of my series blog posts. In previous blog post, we discussed about concept of the linear regression and its mathematical model representation.  We also tried to implement linear regression in R step by step. In this post I will discuss about the logistic regression  and how to implement the The post Logistic...

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Nonlinear Gmm with R – Example with a logistic regression

November 7, 2013
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In this post, I will explain how you can use the R gmm package to estimate a non-linear model, and more specifically a logit model. For my research, I have to estimate Euler equations using the Generalized Method of Moments. I contacted Pierre Chaussé, the creator of the gmm library for help, since I was having...

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Remembering the Gist, But Not the Details: One-Dimensional Representation of Consumer Ratings

October 13, 2013
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Remembering the Gist, But Not the Details:  One-Dimensional Representation of Consumer Ratings

In survey research, it makes a difference how the question is asked.  "How would you rate the service you received at that restaurant?" is not the same as "Did you have to wait to be seated, to order your meal, to be served your food, or to pay yo...

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Logistic regression and categorical covariates

September 26, 2013
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Logistic regression and categorical covariates

A short post to get back – for my nonlife insurance course – on the interpretation of the output of a regression when there is a categorical covariate. Consider the following dataset > db = read.table("http://freakonometrics.free.fr/db.txt",header=TRUE,sep=";") > tail(db) Y X1 X2 X3 995 1 4.801836 20.82947 A 996 1 9.867854 24.39920 C 997 1 5.390730 21.25119 D 998 1...

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R GIS: Polygon Intersection with gIntersection{rgeos}

September 16, 2013
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R GIS: Polygon Intersection with gIntersection{rgeos}

A short tutorial on doing intersections in R GIS. gIntersection{rgeos} will pick the polygons of the first submitted polygon contained within the second poylgon - this is done without cutting the polygon's edges which cross the clip source polygon. For the function that I use to download the example data, url_shp_to_spdf() please see HERE. library(rgeos)library(dismo)URLs...

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R for Ecologists: RLQ analysis (semi) explained

September 3, 2013
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R for Ecologists: RLQ analysis (semi) explained

I’ve been reading about RLQ analysis, also known as the fourth corner method, for analyzing relationships between environmental characteristics and species traits. I was interested because I thought I might be using RLQ analysis to answer a specific set of … Continue reading →

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Estimation, prediction, and evaluation of logistic regression models

August 26, 2013
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I provide an introduction to using logistic regression for prediction (binary classification) using the Titanic data competition from www.Kaggle.com as an example. I use models to predict in missing data, estimate a logistic regression model on a trai...

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