Publications by Marc in the box
Canonical Correlation Analysis for finding patterns in coupled fields
First CCA pattern of Sea Level Pressure (SLP) and Sea Surface Temperature (SST) monthly anomalies for the region between -180 °W to -70 °W and +30 °N to -30 °S. The following post demonstrates the use of Canonical Correlation Analysis (CCA) for diagnosing coupled patterns in climate fields. The method produces similar results to that of M...
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Add a frame to a map
Here is a function that adds a frame of alternating colors to a map (un-projected). One defines the extension of each bar (in degrees) and an optional width of the bars (in inches). It uses the “joinPolys” function of the package to trim the bars near the map corners where the axes meet.the map.frame function:Read more » Related To leave a...
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Working with Globcolour data
The Globcolour project (http://www.globcolour.info/) provides relatively easy access to ocean color remote sensing data. Data is provided at http://hermes.acri.fr/and the following parameters are available:· Chlorophyll-a (CHL1 and CHL2)· Fully normalised water leaving radiances at 412, 443, 490, 510, 531, 550-565, 620, 665-670, 681 and 709 nm ...
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Adding a transparent image layer to a plot
The following example shows how to add a transparent image-type layer to a plot. The add.alpha function (below) simply adds transparency to a vector of colors which is then introduced in the “col” argument of an image plot. Read more » Related To leave a comment for the author, please follow the link and comment on their blog: me nugget. ...
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Create polygons from a matrix
The following function matrix.poly allows for the addition of polygons to a plot based on a matrix and defined matrix positions. I have used this function on occasion to highlight specific matrix locations (e.g. in the above figure). You can do the same by overlaying another image (left in above plot) but with this function you will have all othe...
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DINEOF (Data Interpolating Empirical Orthogonal Functions)
I finally got around to reproducing the DINEOF method (Beckers and Rixon, 2003) for optimizing EOF analysis on gappy data fields – it is especially useful for remote sensing data where cloud cover can result in large gaps in data. Their paper gives a nice overview of some of the various methods that have been used for such data sets. One of the...
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Finding a pin in a haystack – PCA image filtering
I found the following post regarding the anomalous metal object observed in a Curiosity Rover photo to be fascinating – specifically, the clever ways that some programmers used for filtering the image for the object. The following answer on mathematica.stackexchange.com was especially illuminating for its use of a multivariate distribution to d...
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Spirograph with R
Just had to figure out how to replicate this old toy of mine with R! I had no idea how long it's been around:Read more » Related To leave a comment for the author, please follow the link and comment on their blog: me nugget. R-bloggers.com offers daily e-mail updates about R news and tutorials about learning R and many other topics. Click he...
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Producing animated GIFs and Videos
It took me a while to figure out how to use the animation package on my Windows OS. In making an animated GIF, the problem seems to have been quite simple in the end (and I should have been more patient in reading the instructions!) – Following installation of the program ImageMagick, one has to define where the program convert.exe is located u...
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Lomb-Scargle periodogram for unevenly sampled time series
In the natural sciences, it is common to have incomplete or unevenly sampled time series for a given variable. Determining cycles in such series is not directly possible with methods such as Fast Fourier Transform (FFT) and may require some degree of interpolation to fill in gaps. An alternative is the Lomb-Scargle method (or least-squares sp...
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