Controlling string parsing

[gsakkis]

Pint comes with a powerful string parsing that can parse almost arbitrarily complex expressions. In my use case I'd like to limit parsing to a simple "number [unit]" pattern. For example

• "3-8" represents a range instead of a quantity and should raise an exception instead of evaluating to -5.
• "6 +- 1" represents an uncertainty instead of a quantity and should raise an exception instead of evaluating to 5.
• "3/4" represents a fraction and should still be allowed to be parsed as quantity.

Is this possible somehow?

[hgrecco]

For simple things, you can use parse_pattern (See here ). For more complex things, maybe my stringparser package might be useful for you.

[gsakkis]

Thanks, I looked at parse_pattern but it seems it expects a given unit? Or is there a way to parse arbitrary units?

For now I resorted to checking if a regular expression matches before trying to parse it as a quantity.

[hgrecco]

parse_pattern is used to capture known parts of a string, which you can then use to build your own Quantity.