459 search results for "evaluation"

Using mutate from dplyr inside a function: getting around non-standard evaluation

September 23, 2015
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To edit or add columns to a data.frame, you can use mutate from the dplyr package: Here, dplyr uses non-standard evaluation in finding the contents for mpg and wt, knowing that it needs to look in the context of… See more ›

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Bootstrap Evaluation of Clusters

September 4, 2015
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Bootstrap Evaluation of Clusters

Illustration from Project Gutenberg The goal of cluster analysis is to group the observations in the data into clusters such that every datum in a cluster is more similar to other datums in the same cluster than it is to datums in other clusters. This is an analysis method of choice when annotated training data … Continue reading...

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Factor Evaluation in Quantitative Portfolio Management

March 23, 2015
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Factor Evaluation in Quantitative Portfolio Management

When it comes to managing a portfolio of stocks versus a benchmark the problem is very different from defining an absolute return strategy. In the former one has to hold more stocks than in the later where no stocks at all can be held  if there is not good enough opportunity.  The reason for that is the tracking error. This

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Medicines under evaluation

March 15, 2015
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While browsing through the internet I ran into the medicines under evaluation page of the European Medicines Agency. There was a .pdf for each month and I thought it would be interesting to look if I could analyze those data. Each .pdf contains various...

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Tips on non-standard evaluation in R

December 2, 2014
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One of my favorite features of R is its meta-programming facilities. It can be simply demonstrated by the following examples. An ordinary use of R is to do statistical computing. We can evaluate something like sin(0) 0 Meta-programming in R allows users to manipulate the expression to evaluate. We can use quote to create an object that represents a function call. quote(sin(0)) sin(0) In...

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ALUES: Agricultural Land Use Evaluation System, R package

October 26, 2014
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Authors:Arnold R. Salvacion                                                                       [email protected] Analysis and Visualization using R (blog)                                          Al-Ahmadgaid B. Asaad (maintainer)[email protected] Land Use Evaluation System (ALUES) is an R package that evaluates land suitability for different crop production. The package is based on the Food and Agriculture Organization (FAO) and the International Rice Research Institute (IRRI) methodology for land evaluation. Development...

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Moving Beyond CTR: Better Recommendations Through Human Evaluation

October 6, 2014
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Moving Beyond CTR: Better Recommendations Through Human Evaluation

Imagine you're building a recommendation algorithm for your new online site. How do you measure its quality, to make sure that it's sending users relevant and personalized content? Click-through rate may be your initial hope…but after a bit of thought, it's not clear that it's the best metric after all. Take Google's search engine. In many cases, improving the quality...

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Metaprogramming in R with an example: Beating lazy evaluation

September 5, 2013
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Functional languages allows us to treat functions as types. This brings us a distinct advantage of being able to write a code that generates further code, this practise is generally known as metaprogramming. As a functional language R project provides ...

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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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Classification of the Hyper-Spectral and LiDAR Imagery using R (mostly). Part 1: Result Evaluation

July 28, 2013
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Classification of the Hyper-Spectral and LiDAR Imagery using R (mostly). Part 1: Result Evaluation

Introduction There was the EEEI Data Fusion Contest this spring. This year they wanted people to elaborate about hyper-spectral (142-bands imagery) and LiDAR data. The resolution of the data-set was about 5 m.  There were 2 nominations: best classification and  the best scientific paper.  I work with high-resolution imagery quite often, but classification is a very rear task for me...

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