JOSS Review [crvernon]: Include masked regex behavior in documentation about datasailr HOT 5 CLOSED

What I am saying is that whether the first occurrence or the last occurrence takes effect does not come from regular expression's feature. It comes from how the code is executed.

I agree. I didn't want users to be misled by assumptions that there would be some error raised if there were errors within their regular expressions, in terms of duplicated values in the query string. Since these query strings will likely be constructed manually, I believe they are prone to these types user error.

If you believe that the current representation of how this functions is sufficiently represented in your documentation, I will close the issue.

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Thank you for your comment!

Even when ^Hornet appears in regular expressions for both usa and japan, they both work. (i.e. they do not mask each other.)

The following code shows that ^Hornet in usa and ^Hornet in japan work.

library(datasailr)
data(mtcars)

sail(mtcars, '
germany = re/(^Merc|^Porsche|^Volvo)/
usa = re/(^Hornet|^Cadillac|^Lincoln|^Chrysler|^Dodge|^AMC|^Camaro|^Chevrolet|^Pontiac|^Ford)/
japan = re/(^Mazda|^Datsun|^Honda|^Toyota|^Hornet)/

_rowname_ =~ germany
type_germany = rexp_matched(1)
_rowname_ =~ usa
type_usa = rexp_matched(1)
_rowname_ =~ japan
type_japan = rexp_matched(1)
')

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Even when ^Hornet appears in regular expressions for both usa and japan, they both work. (i.e. they do not mask each other.)
The following code shows that ^Hornet in usa and ^Hornet in japan work.

I agree that this situation works; however, when the assignment occurs for a common field (e.g., type) only the first occurrence of the value (Hornet) will be recognized.

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when the assignment occurs for a common field (e.g., type) only the first occurrence of the value (Hornet) will be recognized.

This is true when regular expression matching is conducted in if-else's conditions. (you already seem to have mentioned)

In the following code, the last regular expression matching result overwrites the previous results, because those matching results are assigned to the same field (type).

library(datasailr)
data(mtcars)

sail(mtcars, '
germany = re/(^Merc|^Porsche|^Volvo)/
usa = re/(^Hornet|^Cadillac|^Lincoln|^Chrysler|^Dodge|^AMC|^Camaro|^Chevrolet|^Pontiac|^Ford)/
japan = re/(^Mazda|^Datsun|^Honda|^Toyota|^Hornet)/

_rowname_ =~ germany
type = rexp_matched(1)
_rowname_ =~ usa
type = rexp_matched(1)
_rowname_ =~ japan
type = rexp_matched(1)
')

I am sorry if I misunderstand what you are saying.

What I am saying is that whether the first occurrence or the last occurrence takes effect does not come from regular expression's feature. It comes from how the code is executed.

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I understand. When I make tutorials, I will keep it in mind. Thank you very much for your comments!

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