ODV figures in R with bathymetry

Objective

Nearly four years after writing a blog post about recreating R figures in ODV I had someone reach out to me expressing interest in adding a bathymetry layer over the interpolated data. It’s always nice to know that these blog posts are being found useful for other researchers. And I have to admit I’m a bit surprised that the code still runs 4 years later. Especially considering that it uses the tidyverse which is notorious for breaking backwards compatibility. In order to demonstrate the overlaying of bathymetry data on a CTD transect we will need to use a different dataset than in the previous blog post. One may use any data one would like, but for this blog I went to this shiny app to extract some data from the coast of South Africa. Specifically I filtered for temperature data from November 1990 at all depths. We won’t go back over the theory for recreating the ODV figure in this blog post, so please revisit that for a recap as necessary. Below I will show two of the necessary steps to get interpolated CTD data before we begin on the bathymetry mask.

Analysis of Bio-Oracle data

Objective

While running some brief quality control tests on Bio-Oracle layers before using them for a recent project it was detected that some of the layers in the current version of the Bio-Oracle product appear to have very large errors. Specifically the error is that there are layers where the minimum values are greater than the maximum values. It is unclear how this could be possible, so in the following text and code we will look into how we go about investigating these data layers and we will discuss which layers are fine, and which are not. This error was first detected in the current velocity layers but a brief search turned up errors in other layers, too. So in this post we will be going through each individual layer to test for this max less than min error. We will look at all of the different depths as well as the future projections.

Downloading environmental data in R

Objective

Having been working in environmental science for several years now, entirely using R, I’ve come to greatly appreciate environmental data sources that are easy to access. If you are reading this text now however, that probably means that you, like me, have found that this often is not the case. The struggle to get data is real. But it shouldn’t be. Most data hosting organisations do want scientists to use their data and do make it freely available. But sometimes it feels like the path to access was designed by crab people, rather than normal topside humans. I recently needed to gather several new data products and in classic ‘cut your nose off to spite your face’ fashion I insisted on doing all of it directly through an R script that could be run in RStudio. Besides being stubborn, one of the main reasons I felt this was necessary is that I wanted these download scripts to be able to be run operationally via a cron job. I think I came out pretty successful in the end so wanted to share the code with the rest of the internet. Enjoy.

South Africa time survey

Objective

In South Africa there are a range of idioms for different time frames in which someone may (or may not) do something. The most common of these are: ’now’, ‘just now’, and ’now now’. If one were to Google these sayings one would find that there is general agreements on how long these time frames are, but that agreement is not absolute.

Transects

Preface

This week I have expanded the coastR package with the inclusion of a function that calculates the angle of the heading for alongshore or shore-normal transects. The rest of this blog post is the vignette that I’ve written detailing the set of this function. Next week I’ll likely be taking a break from coastR development to finally create a package for the SACTN dataset. That is a project that has been in the works for a loooong time and it will be good to finally see a development release available to the public.

Sequential sites

Preface

The rest of the blog post after this preface section is a copy of the vignette I’ve written for the first function in the new package I am developing: coastR. This package aims to provide functions that are useful for coastal oceanography but that do not yet exist in the R language. It is not my intention to provide algorithms for physical oceanography as these may already be found elsewhere. This post covers how one may determine the correct sequence of sites along a convoluted coastline.

Polar plot climatologies

Objective

Whilst cruising about on Imgur I found a post about science stuff. Not uncommon, which is nice. These sorts of grab-bag posts about nothing in particular often include some mention of climate science, almost exclusively some sort of clever visualisation of a warming planet. That seems to be what people are most interested in. I’m not complaining though, it keeps me employed. The aforementioned post caught my attention more than usual because it included a GIF, and not just a static picture of some sort of blue thing that is becoming alarmingly red (that was not meant to be a political metaphor). I’m referring to the now famous GIF by climate scientist Ed Hawkins (@ed_hawkins) whose blog may be found here, and the specific post in question here. A quick bit of research on this animation revealed that it has likely been viewed by millions of people, was featured in the opening ceremony of the Rio Olympics, and was created in MATLAB. Those three key points made me decide to do a post on how to re-create this exact figure in R via a bit of reverse engineering. The original GIF in question is below.

Mapping with ggplot2

Objective

There are many different things that require scientists to use programming languages (like R). Far too many to count here. There is however one common use amongst almost all environmental scientists: mapping. Almost every report, research project or paper will have need to refer to a study area. This is almost always “Figure 1”. To this end, whenever I teach R, or run workshops on it, one of the questions I am always prepared for is how to create a map of a particular area. Being a happy convert to the tidyverse I only teach the graphics of ggplot2. I have found that people often prefer to use the ggmap extension to create ggplot quality figures with Google map backgrounds, but I personally think that a more traditional monotone background for maps looks more professional. What I’ve decided to showcase this week is the data and code required to create a publication quality map. Indeed, the following code will create the aforementioned obligatory “Figure 1” in a paper I am currently preparing for submission.

Goats per capita

Objective

A few weeks ago for a post about the relationship between gender equality and GDP/ capita I found a nifty website that has a massive amount of census information for most countries on our planet. Much of this information could be used to answer some very interesting and/ or important questions. But some of the data can be used to answer seemingly pointless questions. And that’s what I intend to do this week. Specifically, which countries in the world have the highest rates of goats/ capita?

Party immigration

Objective

As an immigrant myself, all of the talk of immigration to be found in main stream media outlets today makes me a bit nervous. Whereas most people that speak of the pro’s and con’s of immigration do so from the point of view of how it may affect the country of their birth, I view this issue as something that affects my ability to live outside the country of my birth. I immigrated into the Republic of South Africa in 2013 and have been living here since. I would do a piece on South African immigration but the numbers are difficult to get a hold of and honestly most people are less interest in South Africa than the USA.

ODV figures in R

Objective

With more and more scientists moving to open source software (i.e. R or Python) to perform their numerical analyses the opportunities for collaboration increase and we may all benefit from this enhanced productivity. At the risk of sounding sycophantic, the future of scientific research truly is in multi-disciplinary work. What then could be inhibiting this slow march towards progress? We tend to like to stick to what is comfortable. Oceanographers in South Africa have been using MATLAB and ODV (Ocean Data View) since about the time that Jesus was lacing up his sandals for his first trip to Palestine. There has been much debate on the future of MATLAB in science, so I won’t get into that here, but I will say that the package oce contains much of the code that one would need for oceanographic work in R, and the package angstroms helps one to work with ROMS (Regional Ocean Modeling System) output. The software that has however largely gone under the radar in these software debates has been ODV. Probably because it is free (after registration) it’s fate has not been sealed by university departments looking to cut costs. The issue with ODV however is the same with all Microsoft products; the sin of having a “pointy clicky” user interface. One cannot perform truly reproducible research with a menu driven user interface. The steps must be written out in code. And so here I will lay out those necessary steps to create an interpolated CTD time series of temperature values that looks as close to the default output of ODV as possible.

Wind Vector Time Series

Objective

As more and more physical scientists (e.g. oceanographers) move to R from other object oriented command line programming languages, such as Matlab, there will be more and more demand for the code that is needed to do some basic things that they may already know how to do in their previous languages that they don’t yet know how to do in R. Surprisingly, there are many things that should be very easy to find how to do in R that are not. Or are at least not widely publicized. One such example is how to plot wind vectors as a time series. This is a very necessary part of any analysis of the wind or currents in a particular area. Making it useful broadly to most climate scientists. Try as I might, I’ve only been able to find one source that gives an example of how to plot wind (or current) vectors as a time series with ggplot2 in R. Having now been asked how to do this by several people I thought it would be useful to write up my workflow and put it on the internet so that there is one more source that people searching for answers may find.

Gender and GDP

Objective

Most people living in the Western World are very quick to extol the virtues of gender equality. There are however many places where this is not so. This then inevitably leads to conflict as cultures and nations are drawn closer together on our ever shrinking earth. Perhaps not the sort of conflict that leads to sabre rattling, but certainly ideological disagreements that affect policy and have real impacts on large swathes of humanity. So what is to be done? How can say how anyone else should be. There are of course all sorts of moral back and forth’s that could be pursued cyclically ad nauseum, but what if we could show quantitatively what the benefit of gender equality was to a nation and the lives of it’s people? That is the exact sort of question I like to answer here at this blog and it is a question that came up in my daily life a couple of weeks ago. Because most metrics for most countries are recorded, this is the sort of thing that can be answered. Indeed, it has been before, so here I add another take on an argument that really shouldn’t still be happening…

Religious sentiment

Objective

Before we begin, I would like to acknowledge that the framework for this analysis was adapted from a blogpost found on the wonderfully interesting R-bloggers website. The objective of this analysis is to use sentiment analysis on different religious texts to visualise the differences/ similarities between them. This concept is of course fraught with a host of issues. Not least of which being detractors who will likely not endeavour to engage in rational debate against the findings of this work. This is of course beyond the control of the experimental design so I rather focus here on the issue that the translations of the texts used are not modern, and none of them were written (and generally not intended to be read in) English. Therefore a sentiment analysis of these works will be given to a certain amount of inaccuracy because the sentiment database is a recent project and one must assume that the emotions attached to the words in the English language reflect modern sentiment, and not the emotive responses that were necessarily desired at the time of writing/ translation. That being said, the sentiment that these texts would elicit in a reader today (assuming that anyone actually still reads the source material for their faith) would be accurately reflected by the sentiment analysis project and so this issue is arguably a minor one. As a control group (non-religious text), we will be using Pride and Prejudice, by Jane Austen simply because this has already been ported into R and is readily accesible in the package janeaustenr.