Package for constructing regular expressions via functions

General
#1

My google is failing me. I believe I've seen a package in R that allows you to construct a regular expression step by step. Something like

r = startswith("a") %>% endswith("b") # "^a.*b$"

Can someone remind me the name of the package?

#2

Hi @pdeffebach, could you say a little more about your context, and what you'd like to be able to do? I know of helper functions like those, but they don't produce regular expressions.

#3

Maybe the ore package

#4

I just want to use regex to determine if a string matches a pattern, but you know the saying "you decide to do regex, now you have two problems". A MWE would be

street _names = c("myrtle street", "poplar st", "oak road", "maple rd")
find_streets  = function(street_name) {
    str_detect(street, "st$") | str_detect(street, "street")
}

I remember hearing about a package that allows users to construct something like a regular expression, without worrying about writing a regex itself.

#5

So maybe something like http://buildregex.com/, but in R?

In RStudio, str_view() and str_view_all() can be useful for experimenting with regular expressions; I learned about them in section 14.3 of 'R for Data Science'.

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#6

One aid is regexplain which has the added benefit of being an RStudio plugin. Another possibility is devtools::install_github("VerbalExpressions/RVerbalExpressions")

I haven't used any of these, and didn't see anything else. There may be constructors that you could use in other languages and paste the resulting expressions as a stringr regex pattern that fit in a piped workflow

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#7

Cool! I think I'll be trying that out soon.

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#8

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