selbosh / doseminer Goto Github PK

Thanks for this package. I need to extract doses and units from free text, so I tried this. However, there are some accuracy issues you should probably look into. For example, if you run the code:
extract_from_prescription(c("Diclofenac sodium 50mg gastro-resistant tablets", "Bendroflumethiazide 2.5mg tablets", "Co-amoxiclav 250mg/125mg tablets", "Zyban 150mg modified-release tablets (GlaxoSmithKline UK Ltd)")), you get the wrong units (first two examples), fail to detect the clavulanate dose (third example) and extract a non-existent frequency (last example).

1. dealing with extra/double space
2. recognising lunchtime and teatime in addition to morning|night|bedtime

The package currently supports expressions with half measures in them, including mixed fractions:

doseminer::replace_numbers(c('half a spoonful', 'three and a half tablets'))
## [1] "0.5 a spoonful" "3.5 tablets" 

But more unusual fractions like thirds, fifths and quarters don't really work because it just kind of adds the denominator:

doseminer::replace_numbers(c('thirty three and a third', 'four fifths'))
## [1] "37" "9" 

The problem is with fixing this (assuming such cases appear often enough in prescriptions to be worth worrying about) without unintentionally breaking the parsing of ordinal words, which look a lot like fractions:

doseminer::replace_numbers(c('every third day', 'every fifth hour'))
## [1] "every 3 day"  "every 5 hour"

However with enough ambition, 'every 1/3 day' could be interpreted as '(every day) / 3' and end up giving the right result, with an appropriate redesign of how intervals are calculated.