3408 search results for "gis"

updating the GISS dataset

November 6, 2015
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Introduction I was watching a video of David Suzuki being interviewed on Australian TV, and there were some questions about the “pause” in temperature in the GISS dataset. I thought I’d like to check for myself, and reasoned that I may as well update the giss dataset in the ocedata R package. As always seems to be the case, the data format is changed...

My QGIS Processing Scripts at GitHub

October 22, 2015
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This is probably my shortest post ever.All my QGIS processing scripts (R and Python) and models that I already blogged about, plus some extra are now available at GitHub.

Predicting creditability using logistic regression in R: cross validating the classifier (part 2)

September 15, 2015
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Now that we fitted the classifier and run some preliminary tests, in order to get a grasp at how our model is doing when predicting creditability we need to run some cross validation methods.Cross validation is a model evaluation method that does not use conventional fitting measures (such as R^2 of linear regression) when trying to evaluate the model....

How to perform a Logistic Regression in R

September 13, 2015
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Logistic regression is a method for fitting a regression curve, y = f(x), when y is a categorical variable. The typical use of this model is predicting y given a set of predictors x. The predictors can be continuous, categorical or a mix of both. The categorical variable y, in general, can assume different values.

Logistic Regression in R – Part Two

September 2, 2015
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$Logistic Regression in R – Part Two$

My previous post covered the basics of logistic regression. We must now examine the model to understand how well it fits the data and generalizes to other observations. The evaluation process involves the assessment of three distinct areas – goodness of fit, tests of individual predictors, and validation of predicted values – in order to

Predicting creditability using logistic regression in R (part 1)

September 2, 2015
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As I said in the previous post, this summer I’ve been learning some of the most popular machine learning algorithms and trying to apply what I’ve learned to real world scenarios. The German Credit dataset provided by the UCI Machine Learning Repository is another great example of application.The German Credit dataset contains 1000 samples of applicants asking for...

Logistic Regression in R – Part One

September 1, 2015
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$Logistic Regression in R – Part One$

Please note that an earlier version of this post had to be retracted because it contained some content which was generated at work. I have since chosen to rewrite the document in a series of posts. Please recognize that this may take some time. Apologies for any inconvenience.   Logistic regression is used to analyze the

Searching Twitter with ArcGIS Pro Using R

August 18, 2015
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I committed to testing this a long time ago, however, a number of other projects intervened, so I have only just got around to writing up this short tutorial. One of the exciting things from the ESRI Developers Conference this year was the launch of the R-ArcGIS bridge. In simple terms, this enables you to run R...

Searching Twitter with ArcGIS Pro Using R

August 18, 2015
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I committed to testing this a long time ago, however, a number of other projects intervened, so I have only just got around to writing up this short tutorial. One of the exciting things from the ESRI Developers Conference this year was the launch of the R-ArcGIS bridge. In simple terms, this enables you to run R...

Evaluating Logistic Regression Models

August 17, 2015
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Logistic regression is a technique that is well suited for examining the relationship between a categorical response variable and one or more categorical or continuous predictor variables. The model is generally presented in the following format, where β refers to the parameters and x represents the independent variables. log(odds)=β0+β1∗x1+...+βn∗xn The log(odds), or log-odds ratio, is defined