How to use pipe operator in Mathematica?

In order to utilize the post fix operator // in WL in the way the R library magrittr implements/uses %>% several things have to be kept in mind.

• R's magrittr operator %>% :

  1. Assumes that the pipeline value is the first and only argument by default

     • Many of the tidyverse package functions rely heavily on this

  2. If a function needs only the first argument to be specified only the function name can be used

  3. Different argument location of the pipeline value can be specified with .

• In WL using the operator // :

  1. Often translating R tidyverse pipeline workflows in WL pipelines with // requires the argument location specification of the pipeline object

  2. If a function needs only one argument to be specified only the function name can be used

  3. The argument slot specification #1 should be used (instead of . of R's magrittr.)

Clarification examples follow.

Example 1

R-magrittr:

 iris %>% nrow %>% runif

WL:

ExampleData[{"Statistics", "FisherIris"}] // Length // RandomReal[1, #1] &

Example 2

R-magrittr:

 iris %>% nrow %>% runif( n = 3, min = -10, max = .) 

WL:

ExampleData[{"Statistics", "FisherIris"}] // Length //  RandomReal[{-10, #1}, 3] &

Note that in addition to the postfix notation //, you can also set up a pipeline of operators with RightComposition (/*) that can be re-used later. For example:

pipeline = Map[f] /* Apply[g] /* h
Range[5] // pipeline
Range[10] // pipeline

(* this also works, though it's maybe less intuitive *)
pipeline @ Range[5]

You can also use Composition (@*) if you prefer to read the other way around (i.e., the functions closest to the argument get applied first):

pipeline2 = h @* Apply[g] @* Map[f]
pipeline2 @ Range[5]