Publications by John Mount
Timing the Same Algorithm in R, Python, and C++
While developing the RcppDynProg R package I took a little extra time to port the core algorithm from C++ to both R and Python. This means I can time the exact same algorithm implemented nearly identically in each of these three languages. So I can extract some comparative “apples to apples” timings. Please read on for a summary of the res...
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A Beautiful 2 by 2 Matrix Identity
While working on a variation of the RcppDynProg algorithm we derived the following beautiful identity of 2 by 2 real matrices: The superscript “top” denoting the transpose operation, the ||.||^2_2 denoting sum of squares norm, and the single |.| denoting determinant. This is derived from one of the check equations for the Moore–Penrose in...
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R Tip: Use seqi() For Indexes
R Tip: use seqi() for indexing. R‘s “1:0 trap” is a mal-feature that confuses newcomers and is a reliable source of bugs. This note will show how to use seqi() to write more reliable code and document intent. The issue is, contrary to expectations (formed in working with other programming languages) the sequence 1:0 is not empty. It is i...
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Practical Data Science with R, 2nd Edition discount!
Please help share our news and this discount. The second edition of our best-selling book Practical Data Science with R2, Zumel, Mount is featured as deal of the day at Manning. The second edition isn’t finished yet, but chapters 1 through 4 are available in the Manning Early Access Program (MEAP), and we have finished chapters 5 and 6 which a...
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R Tip: Use Inline Operators For Legibility
R Tip: use inline operators for legibility. A Python feature I miss when working in R is the convenience of Python‘s inline + operator. In Python, + does the right thing for some built in data types: It concatenates lists: [1,2] + [3] is [1, 2, 3]. It concatenates strings: 'a' + 'b' is 'ab'. And, of course, it adds numbers: 1 + 2 is 3. The i...
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Make Teaching R Quasi-Quotation Easier
To make teaching R quasi-quotation easier it would be nice if R string-interpolation and quasi-quotation both used the same notation. They are related concepts. So some commonality of notation would actually be clarifying, and help teach the concepts. We will define both of the above terms, and demonstrate the relation between the two concepts. ...
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Fully General Record Transforms with cdata
One of the design goals of the cdata R package is that very powerful and arbitrary record transforms should be convenient and take only one or two steps. In fact it is the goal to take just about any record shape to any other in two steps: first convert to row-records, then re-block the data into arbitrary record shapes (please see here and here ...
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Function Objects and Pipelines in R
Composing functions and sequencing operations are core programming concepts. Some notable realizations of sequencing or pipelining operations include: Unix’s |-pipe CMS Pipelines. F#‘s forward pipe operator |>. Haskel’s Data.Function & operator. The R magrittr forward pipe. Scikit-learn‘s sklearn.pipeline.Pipeline. The idea is: many imp...
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cdata Control Table Keys
In our cdata R package and training materials we emphasize the record-oriented thinking and how to design a transform control table. We now have an additional exciting new feature: control table keys. The user can now control which columns of a cdata control table are the keys, including now using composite keys (that is keys that are spread acro...
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PDSwR2 Free Excerpt and New Discount Code
Manning has a new discount code and a free excerpt of our book Practical Data Science with R, 2nd Edition: here. This section is elementary, but things really pick up speed as later on (also available in a paid preview). Related To leave a comment for the author, please follow the link and comment on their blog: R – Win-Vector Blog. R-blogg...
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