Question

I working with some regular expression matching and I’m trying to figure out how you would exclude a specific character pattern. Specifically, I want to exclude the following pattern:

5 -       #in words: digit, space, dash & space)

I know how to exclude the components individually: [^5 ^-] but I’m looking to exclude the specific pattern. Is this possible?

Update – I’m using Ruby as my programming language.

Here is some sample input and desired output.:

Input:  1 - Blue-Stork Stables; 2 - Young, Robert, S.; 3 - Seahorse Stable; 4 - Carney, Elvis; 5 - Guerrero, Juan, Carlos-Martin; 6 - Dubb, Michael; 7 - Summers, Hope; 8 - DTH Stables; 9 - Peebles, Matthew\n

the desired output would be:

Output: Blue-Stork Stables; Young, Robert, S.; Seahorse Stable; Carney, Elvis; Guerrero, Juan, Carlos-Marting; Dubb, Michael; Summers, Hope; DTH Stables; Peebles, Matthew\n

Please take note of the dashes on Blue-Stork Stables and Juan Carlos-Martin.

Answer 1

EDIT: So you mean “remove”, not “exclude”. No problem:

result = subject.gsub(/\d+ - /, '')

transforms your input into the desired output. I’ve taken the liberty to allow more than one digit (after all, if numbers reach 10 or higher, you probably want to remove those entirely, too. Right?).

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(Old answer for “historical reasons”)

Depending on what you mean by “exclude”, it appears that you’re looking for negative lookahead assertions:

^(?!.*\d - )

will fail on strings that contain 5 - anywhere and succeed on all other strings:

"5 - "       // fail
"5 -"        // match
"abc5 - xyz" // fail
"foobar5 - " // fail