seplyr is an R package that makes it easy to program over dplyr 0.7.*.
To illustrate this we will work an example.
Continue reading Tutorial: Using seplyr to Program Over dplyr
Tag: non-standard evaluation
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.
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.
Continue reading Non-Standard Evaluation and Function Composition in R
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:
wrapr: for sweet R code
This article is on writing sweet R code using the wrapr package.
My recent BARUG talk: Parametric Programming in R with replyr
I want to share an edited screencast of my rehearsal for my recent San Francisco Bay Area R Users Group talk: