stringfix : new R package for string manipulation in a %>% way

December 8, 2018
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I usually write around here in french and mainly report on French Hospitals data managment and the statistical tasks they imply. As today’s post is about a new package I have created, I’ll be writing in english. The package is called stringfix because it uses infix operators to manipulate character strings.

Introduction

In Python, the operator + is used to paste two character strings together. For example: 'Hello ' + 'world' gives 'Hello World'. For that matter, building sentences with words and arithmetic symbols seems a very nice way to write. In R, the paste function requires parenthesis in order to be computed. Therefore the use of consecutive functions can make it hard to understand.

+ is a nice operator, and we can use it in R almost as it is used in Python by creating an infix operator.

`%+%` <- function(x,y){
  paste0(x, y)
}

While a ggplot function has already the same name, it is used to override data in a ggplot call and not for pasting character strings, see here. When loading tidyverse, the same ggplot function is called, preventing us from using paste0’s %+%. Otherwise, you can find a hint of character string pasting in the Advanced R book.

In order to create a toolbox around paste0’s %+%, I started collecting some other infix functions for character strings manipulation. The main question was: which functions with a right to left call that I use really often could be reordered in a %>% code. Here is the little family I have since build on : paste, grepl, substring, count, padding. The goal of this package is to use stringr or base functions in backend as a start for an alternative character string manipulation in R.

This package is still at its early begining (kind of a draft for me!) but I thought some other people would enjoy it and may even wish to contribute.

Presentation

"In a manner of coding, I just want to say..." % % "Nothing."
#>[1] "In a manner of coding, I just want to say... Nothing."

Examples

paste

'Hello ' %+% 'world'
#> [1] "Hello world"
'Your pastas taste like ' %+% '%>%'
#> [1] "Your pastas taste like %>%"
'coco' %+% 'bolo'
#> [1] "cocobolo"
'Hello' % % 'world'
#> [1] "Hello world"
'Your pastas taste like' % % '%>%'
#> [1] "Your pastas taste like %>%"
'Hello' %,% 'world...'
#> [1] "Hello, world..."
'Your pastas taste like ' %+% '%>%...' %,% 'or %>>%...'
#> [1] "Your pastas taste like %>%..., or %>>%..."

grepl

Case sensitive
'pig' %g% 'The pig is in the cornfield'
#> [1] TRUE
'Pig' %g% 'The pig is in the cornfield'
#> [1] FALSE
Case insensitive (ignore.case)
'pig' %gic% 'The pig is in the cornfield'
#> [1] TRUE
'PIG' %gic% 'The PiG is in the cornfield'
#> [1] TRUE

substring

'NFKA008' %s% '1.4'
#> [1] "NFKA"
'NFKA008' %s% .4
#> [1] "NFKA"
'where is' % % ('the pig is in the cornfield' %s% '1.7') %+% '?'
#> [1] "where is the pig?"

count

fruit <- c("apple", "banana", "pear", "pineapple")
"a" %count% fruit
#> [1] 1 3 1 1
c("a", "b", "p", "p") %count% fruit
#> [1] 1 1 1 3

pad, lpad and rpad

5 %lpad% '0.5'
#> [1] "00005"
5 %lpad%   .5
#> [1] "00005"
5 %lpad%  '.5'
#> [1] "    5"
5 %lpad% '2.5'
#> [1] "22225"
'é' %lpad% 'é.5'
#> [1] "ééééé"

names of tibbles : tolower and toupper

I have added two functions that I use really often.

library(magrittr)
iris %>% toupper_names %>% head
#>   SEPAL.LENGTH SEPAL.WIDTH PETAL.LENGTH PETAL.WIDTH SPECIES
#> 1          5.1         3.5          1.4         0.2  setosa
#> 2          4.9         3.0          1.4         0.2  setosa
#> 3          4.7         3.2          1.3         0.2  setosa
#> 4          4.6         3.1          1.5         0.2  setosa
#> 5          5.0         3.6          1.4         0.2  setosa
#> 6          5.4         3.9          1.7         0.4  setosa

Finally, I also wanted to outline that the function from the rmngb package : %out% : negation of %in% can be very useful to avoid typing ! x %in% y (you can just type x %out% y instead). This is why I have included it in this package !

More information here : https://github.com/GuillaumePressiat/stringfix


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