I want to select the word "hazardous" only if it is a separate word and not with "non " or "non-"before it.

eg:

non-hazardous

non hazardous

hazardous

non agricultural hazardous

regex 1: ^(?!non[-/s]?)hazardous$
regex 2: ^(?!non-|non\s)hazardous$

I tried the above two regex and it gave correct results for the first 3 sentences, but it's not selecting hazardous in 4th sentence. I want to select hazardous in 4th sentence as it doesn't have "non " or "non-" before it

Reference: Regular Expression - Match pattern that does not contain a string

CodePudding user response：

You can use

r'\b(?<!\bnon[-\s])hazardous\b'

See the regex demo. The pattern matches

• \b - a word boundary
• (?<!\bnon[-\s]) - a negative lookbehind that fails the match if there is non- or non and a whitespace immediately to the left of the current location
• hazardous - a string
• \b - a word boundary.