`TÜRKİYE` a valid spelling?

[cjyetman]

The list-one.xls that we use from https://www.six-group.com/en/products-services/financial-information/data-standards.html to get the ISO4217 codes in get_iso4217.R (or better, will use once the URL is updated in an PR #348) uses TÜRKİYE (note the İ). Is this a valid spelling we should support?

[vincentarelbundock]

Probably relevant: https://en.wikipedia.org/wiki/%C4%B0#:~:text=%C4%B0%2C%20or%20i%2C%20called%20dotted,Kazakh%2C%20Tatar%2C%20and%20Turkish.

[NilsEnevoldsen]

Do we not support that? We definitely should. It's just the capital form of "i" in Turkish.

[NilsEnevoldsen]

Does our regex engine have an equivalent of CultureInvariant, or is that a dotnet-exclusive nicety?

[vincentarelbundock]

Does our regex engine have an equivalent of CultureInvariant, or is that a dotnet-exclusive nicety?

Oh, that's neat. I had to google it because I had never heard of this flag. Also funny that the C# docs use exactly our problematic case as their main example.

Maybe I missed something, but I don't think grep(perl=TRUE) supports this out of the box.

[cjyetman]

We currently rely on ignore.case = TRUE in our grepl() command here: https://github.com/vincentarelbundock/countrycode/blob/848e9ce363026c98a38daac9777005925f18f582/R/countrycode.R#L280-L281

Should we consider casting all strings-to-match with tolower() before using grepl()? Probably a small performance hit, but maybe worth it. If we ensure that all of our regexes are lowercase, we could then maybe remove the ignore.case = TRUE, which would probably give a small performance boost.

turkey <- "TÜRKİYE"

countrycode::countrycode(turkey, "country.name", "country.name")
#> Warning: Some values were not matched unambiguously: TÜRKİYE
#> [1] NA

tolower(turkey)
#> [1] "türkiye"
countrycode::countrycode(tolower(turkey), "country.name", "country.name")
#> [1] "Turkey"

turkey.en.regex <- countrycode::codelist$country.name.en.regex[match("TUR", countrycode::codelist$iso3c)]
grepl(x = turkey, pattern = turkey.en.regex, perl = TRUE, ignore.case = TRUE)
#> [1] FALSE
grepl(x = tolower(turkey), pattern = turkey.en.regex, perl = TRUE, ignore.case = TRUE)
#> [1] TRUE
grepl(x = tolower(turkey), pattern = turkey.en.regex, perl = TRUE, ignore.case = FALSE)
#> [1] TRUE

[vincentarelbundock]

FWIW, I don't have a view and not a real good sense of whether this can cause problems (probably not?).

[cjyetman]

It's not the most precise solution, but might capture similar issues with other extended characters, while seemingly not changing the logic at all.

A more precise solution could be to add İ to the regexes for Turkey...

turkey.en.regex <- countrycode::codelist$country.name.en.regex[match("TUR", countrycode::codelist$iso3c)]

grepl(x = c("Turkey", "Turkiye", "Türkiye", "TÜRKİYE"), pattern = turkey.en.regex, perl = TRUE, ignore.case = TRUE)
#> [1]  TRUE  TRUE  TRUE FALSE

turkey.en.regex
#> [1] "turkey|t(ü|u)rkiye"
turkey.en.regex_mod <- "turkey|t(ü|u)rk(i|İ)ye"

grepl(x = c("Turkey", "Turkiye", "Türkiye", "TÜRKİYE"), pattern = turkey.en.regex_mod, perl = TRUE, ignore.case = TRUE)
#> [1] TRUE TRUE TRUE TRUE

side note: I don't know why we use () (capture groups) instead of []

turkey.en.regex_mod <- "turkey|t[ü|u]rk[i|İ]ye"
grepl(x = c("Turkey", "Turkiye", "Türkiye", "TÜRKİYE"), pattern = turkey.en.regex_mod, perl = TRUE, ignore.case = TRUE)
#> [1] TRUE TRUE TRUE TRUE

[vincentarelbundock]

Let's just go with the more precise option, then, as there are fewer unknowns.

What's the benefit of ()? We don't want to capture anything...

[cjyetman]

Let's just go with the more precise option, then, as there are fewer unknowns.

👍🏻

What's the benefit of ()? We don't want to capture anything...

I have no idea. Honestly, I'm somewhat surprised that it works as expected using (). My understanding is that "character class" ([]) is the proper way of matching any one of a list of characters. At some point, a bunch of capture groups (()) got introduced into the regexes here.

[vincentarelbundock]

weird. I can see it for lookaheads and such... oh well!