Category Archives: science

igraph to calculate the internal PageRank of websites

plot graph website for SEO analysis
Graph of an ecommerce website where the nodes are webpages and the edges, links between them
Analysing websites internal linking is key to understand their architecture of information and web structure and thus their potential of Search Engine Optimization, SEO.

Graphs are made of nodes and edges. In SEO nodes are webpages and edges, links directed to them from other webpages on the graph.

library(igraph)
dat=read.csv(file.choose(),header=TRUE) # choose an edgelist in .csv file format
g=graph.data.frame(dat,directed=TRUE)
transitivity(g)

Transitivity or clustering coefficient is the probability that the adjacent vertices of a vertex are connected.

Count vertices vcount(graph)
Count edges ecount(graph)

Diameter
diameter(graph)
The diameter of a graph is the length of the longest geodesic.

Graph density
graph.density(graph)
The density of a graph is the ratio of the number of edges and the number of possible edges.

Find more about plotting directed graphs here.

Juvenile swift stranded in Luarca, Spain

A nestling swift (Apus apus) was lying in the ruins of a house at one meter over street level. It didn´t look injured. We did not touch it.

The pictures were taken in the first week of August in Luarca, a seaside village in the north of Spain.

Swift chick Luarca
Swift chick Luarca
Swift frontal closed eyes
Detail frontal closed eyes
Detail of head of swift chick
Detail of head of swift chick

We spent as little time as possible taking the photos. We did not see the parents coming in to feed the chick in the 5 minutes that we stood waiting at a safe distance.

The first fledgings show up around July 27th in Asturias, Spain, upon the phenology records. There is a great guide to take care of fallen chicks: Swift First Aid.

First arrival dates of swifts are a popular phenology record. Swifts in London arrive in April and May. I think that the duration of stay for Common Swift presence on the nest is a more interesting metric than the first arrival. Surprisingly, this metrics is still poorly studied in Europe (Tigges, U., 2007, The Phenology of the Common Swift Apus apus in Eurasia and the Problem of Defining the Duration of their Stay).

The right amount of sex, kinky neardenthals and walking Easter Island statues

Is it possible to have just the right amount of sex? The mangrove rivulus (Kryptolebias marmoratus) combines self-fertilization with occasional sex to keep the best genes providing immunity to pathogens http://bit.ly/TGh87t

Kinky neardenthals could party hard in feather garments and all, reported from Gibraltar.

Some of the micro pictures selected by the Small World Photomicrography Competition

 

Replicas of Easter Island statues walking with a bit of help of idle holidaymakers by the look of it.

Coyotes took to trotting after joggers in public parks in the US. People took to shooting them down (the coyotes). Projectcoyote.org is working to raise the awareness about the behaviour of the coyotes. Which makes me wonder, if wolves are learning to coexist with humans in Spain, why foxes don’t live in cities and towns in Spain like they do in the United Kingdom?