# Blog Archives

## Great circles, raster, sp and lattice

Recently I found a post at FlowingData with a detailed tutorial to map connections with great circles with R. The tutorial of FlowingData is excellent, but I feel more comfortable with the sp classes and methods, and with the lattice and latticeExtra packages. Besides, I want to use the free spatial data available from the

## Sustainable Futures conference in Manchester

Recently, Kevin Ummel gave a short conference about his PhD research at the Sustainable futures – Tyndall Centre researchers’ international conference. His work, named “Optimizing worldwide deployment of wind and solar power technologies via a high resolution, linear programming model”, is built with R. He is using the solaR package for the solar irradiance calculations,

## Here comes the sun

The solar irradiance incident outside the earth’s atmosphere is called the extraterrestial or extra-atmospheric irradiance. It is derived from the solar constant only with geometric equations. It can be easily calculated with the calcSol function of the solaR package. With this post I will show an example with some packages from the Spatial task view.

## Alpha shapes with R and lattice

What are the alpha shapes?: “The concept of alpha shapes formalizes the intuitive notion of “shape” for spatial point set data, which occurs frequently in the computational sciences. An alpha shape is a concrete geometric object that is uniquely defined for a particular point set. Alpha shapes are generalizations of the convex hull. Given a

The Atmospheric Science Data Center (ASDC) at NASA Langley Research Center offers several data sources. For example, it is possible to download a text file with the 22-year (July 1983 – June 2005) monthly and annual average of global horizontal irradiation. nasafile <- 'http://eosweb.larc.nasa.gov/sse/global/text/global_radiation' nasa <- read.table(file=nasafile, skip=13, header=TRUE) With this data, R and the

## Violin and boxplots with lattice and R

A violin plot is a combination of a boxplot and a kernel density plot. Lattice includes the panel.violin function for this graphical tool. This example draws a violin and a boxplot together. First, let’s download some solar radiation data from the NASA webpage: nasafile <- 'http://eosweb.larc.nasa.gov/sse/global/text/global_radiation' nasa <- read.table(file=nasafile, skip=13, header=TRUE) Now, I plot a

## merge with solaR

The version 0.22 of solaR includes a new method, mergesolaR. It is designed to merge daily time series of several solaR objects. For example, we can obtain the daily irradiation of the whole set of meteorological stations of Madrid (Spain) and use this information to calculate the productivity of a grid connected PV system. It

## solaR 0.22 is at CRAN

The version 0.22 of solaR is now available at CRAN. Besides, solaR is now registered at R-Forge. A new mergesolaR method has been defined for merging solaR objects. The calculation of the sunset time has been improved. The voltage dependency of the efficiency curve of the inverter is now included in fProd and calcGCPV. The

## How to display scatter plot matrices with R and lattice

In lattice, there is a function called splom for the display of scatter plot matrices. For large datasets, the panel.hexbinplot from the hexbin package is a better option than the default panel. As an example, let’s use some meteorological data from MAPA-SIAR: library(solaR) library(hexbin) aranjuez <- readMAPA(prov=28, est=3, start='01/01/2004', end='31/12/2010') aranjuezDF <- subset(as.data.frame(getData(aranjuez)), select=c('TempMedia', 'TempMax',

## Building a fact-based world view

January 7, 2011
By

Gapminder is an independent foundation based in Stockholm, Sweden. Its mission is “to debunk devastating myths about the world by offering free access to a fact-based world view“. They provide free online tools, data (more than 400 datasets freely available!) and videos “to better understand the changing world“. The initial development of Gapminder was the