non-standard evaluation – Win-Vector Blog

April 2, 2018John MountCoding, Opinion, Pragmatic Data Science, Statistics, Tutorialsdplyr, non-standard evaluation, R, R tips, R tricks, seplyr, standard evaluation, wrapr

R Tip: Think in Terms of Values

R tip: first organize your tasks in terms of data, values, and desired transformation of values, not initially in terms of concrete functions or code.

I know I write a lot about coding in R. But it is in the service of supporting statistics, analysis, predictive analytics, and data science.

R without data is like going to the theater to watch the curtain go up and down.

(Adapted from Ben Katchor’s Julius Knipl, Real Estate Photographer: Stories, Little, Brown, and Company, 1996, page 72, “Excursionist Drama 2”.)

Usually you come to R to work with data. If you think and plan in terms of data and values (including introducing more data to control processing) you will usually work in much faster, explainable, and maintainable fashion.

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July 22, 2017July 22, 2017John MountCoding, data science, Opinion, Programming, Statistics, Tutorialsdplyr, non-standard evaluation, R, seplyr, standard evaluation13 Comments

Tutorial: Using seplyr to Program Over dplyr

seplyr is an R package that makes it easy to program over dplyr 0.7.*.

To illustrate this we will work an example.

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June 18, 2017July 11, 2017John MountCoding, Programming, Statistics, Tutorialsnon-standard evaluation, NSE, R, wrapr

wrapr Implementation Update

Introduction

The ~~development version~~ CRAN version of our R helper function wrapr::let() has switched from string-based substitution to abstract syntax tree based substitution (AST based substitution, or language based substitution).

I am looking for some feedback from wrapr::let() users already doing substantial work with wrapr::let(). If you are already using wrapr::let() please test if the current development version of wrapr works with your code. If you run into problems: I apologize, and please file a GitHub issue.

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June 16, 2017July 22, 2017John MountCoding, data science, Opinion, Programming, Statistics, Tutorialsdplyr, function composition, functional programming, non-standard evaluation, NSE, R, R as it is, referential transparency, replyr, SE, wrapr10 Comments

Non-Standard Evaluation and Function Composition in R

In this article we will discuss composing standard-evaluation interfaces (SE: parametric, referentially transparent, or “looks only at values”) and composing non-standard-evaluation interfaces (NSE) in R.

In R the package tidyeval/rlang is a tool for building domain specific languages intended to allow easier composition of NSE interfaces.

To use it you must know some of its structure and notation. Here are some details paraphrased from the major tidyeval/rlang client, the package dplyr: vignette('programming', package = 'dplyr')).

":=" is needed to make left-hand-side re-mapping possible (adding yet another "more than one assignment type operator running around" notation issue).
"!!" substitution requires parenthesis to safely bind (so the notation is actually "(!! )", not "!!").
Left-hand-sides of expressions are names or strings, while right-hand-sides are quosures/expressions.

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March 17, 2017John MountCoding, OpinionLisp, macros, non-standard evaluation, R, standard evaluation1 Comment

Another R [Non-]Standard Evaluation Idea

Jonathan Carroll had a an interesting R language idea: to use @-notation to request value substitution in a non-standard evaluation environment (inspired by msyql User-Defined Variables).

He even picked the right image:

PandorasBox Continue reading Another R [Non-]Standard Evaluation Idea