Writings about

research + light + plants + R + data + plots

Published

2026-04-30

Modified

2026-04-30

Contents at the website relates to subjects that I teach and/or do research on: R language, data visualization, data analysis, the daylight spectrum, measurement of light and optical properties and how plants perceive and respond to the light environment in which they grow.

I add new material regularly. However, the site also rescues and updates content still relevant, written during the last 30 years for my earlier websites and blogs. These other websites no longer exist except as archived by the Wayback Machine or are no longer maintained. Because of this history, the site is organized in sections focusing on different subjects.

New and updated

These “articles” are tutorials or explanations. I have used R for examples, but the aim is mainly to describe methods and approaches related to data analysis and visualization. Several of these articles are based on material prepared for courses or talks.

The R-code gallery contains articles that demonstrate the use of R and R packages, mostly my own packages together with other packages. Each article contains multiple R-code recipes for plotting and computations, cookbook style. The aim is to provide additional examples or recipes complementing those in the packages’ documentation and the well known Cookbook for R website. I check the code examples regularly, and update them when needed.

The SenPEP blog contains posts and articles related to my scientific research with plants and crops: Sensory Ecology and Photobiology of Plants (SenPEP). Some of the contents are news, such as accounts of visits, visitors or specially signiificant publications, while others are articles with accesible introductions to some of the past and current research topics that myself and collaborators have an interest in.

The best way to remain up-to-date about the contents of this site is to use an RSS feed reader such as NetNewsWire (iPhone) or a browser add-on like “FeedBro” (Firefox) and subscribe to the feeds you are interested in. The RSS entry in the site’s main menu contains links to three separate feeds, for the Pages and R Gallery sections of the website.

I publish occasionally announcements through Mastodon. I use hashes to differentiate posts by subject so that you can follow what you are interested in without cluttering your Mastodon Home. You can see my first post through Mastodon or my first toot.

You can visit my Mastodon profile at https://mastodon.social/@aphalo. I am no longer using Twitter/X or Facebook.

For easier reading, contents lists by section are the main ones (see Contents menu entry). A whole-site contents list and lists on specific subjects are also available. These index pages list a selection of posts that are also listed in other index pages. They are only a convenience.

The site is searchable, and the search is based on a static index. Pages are tagged by category and have keywords assigned.

The site menu has the following entries:

  • Contents: Tables of contents for different sections and the whole site.
  • Books: Books I have written or edited.
  • Data: Access data acquired at a weather station located in the Viikki Campus of the University of Helsinki, in Helsinki, Finland.
  • R packages: General information about packages that I maintain, published through CRAN and/or through R-Universe.
  • R4P packages: Web sites of packages included in the R for Photobiology suite, published through CRAN and/or through R-Universe.
  • About: Information about the site and myself.
  • Feeds: RSS feeds by website section and for the whole site.