Monthly Archives: January 2013

What’s that “pre- and post-multiply” stuff?

January 5, 2013
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Often in SEM scripts you will see matrices being pre- and post-multiplied by some other matrix. For instance, this figures in scripts computing the genetic correlation between variables. How does pre- and post-multiplying a variance...

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National identification number: Finland part 3

January 5, 2013
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Last part of our short series about the Finnish social security number (Fssn). You can check part 1 here, and part 2 here.This last post we are interested in generating random Fssn's. This has no real world applications. It is just a coding excercis...

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National identification number: Finland part2

January 5, 2013
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Continuing our theme from last time. The Finnish social security number (FSSn) has the form xxxxxxyzzzq, where the check digit is q.If you want to check if the FSSn is real the check digit is matched to the remainder of xxxxxxzzz / 31. The check di...

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Calling R Functions from C++

January 5, 2013
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At its very essence, Rcpp permits easy access to native R objects at the C++ level. R objects can besimple vectors, list or matrices;compound data structures created from these;objects of S3, S4 or Reference Class vintage; orlanguage objects a...

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Find Out Available Usernames with R

January 5, 2013
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Update on 2013/01/05: Xiao Nan in the comments pointed out that apply(combn(letters, 2), 2, paste0, collapse = '') was wrong for all two-letter usernames, and indeed it was. It is not a combination problem. Now I use his elegant outer() solution. One can also use expand.grid(letters, letters).Github decided to take off their downloads service, and I was very...

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Monotonic deshrinking in weighted averaging models

January 5, 2013
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Monotonic deshrinking in weighted averaging models

Weighted averaging regression and calibration is the most widely used method for developing a palaeolimnological transfer function. Such models are used to reconstruct properties of the past lake environment such as pH, total phosphorus, and water temperature with, it has to be said, varying degrees of success and usefulness. In simple weighted averaging (WA) there is little to specify other...

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IBS reversion edge with QuantShare

January 4, 2013
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IBS reversion edge with QuantShare

Happy New Years to readers; my resolution this year is to continue delivering thoughts and ideas to others in the hopes that we all might be able to benefit somewhat from sharing observations. I'll start by describing an edge using QuantShare as the b...

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PLS Path Modeling with R

January 4, 2013
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PLS Path Modeling with R

Today I’m very happy and so excited to announce my new book PLS Path Modeling with R, freely available in pdf format at:  www.gastonsanchez.com/PLS_Path_Modeling_with_R.pdf After working and writing insanely for a couple of months in the last quarter of 2012, I’ve finally achieved this personal milestone that means so much to me.  What started as a … Continue reading...

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Solving 9-puzzle with GNU R

January 4, 2013
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Solving 9-puzzle with GNU R

During holiday break I have decided to solve 9-puzzle, which is 3x3 variant of a well known 15-puzzle. The solution has proven to be a nice application of igraph package. Warning: this time the code takes a bit more tame than usual in my...

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New AQP Tutorials

January 4, 2013
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New AQP Tutorials

Soil Series Extent Several new AQP-related tutorials have been posted to the R-Forge project page.SoilProfileCollection class/method documentation soil series extent mapping examplesread more

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