icd9GetMajor: Get major (three-digit) part of ICD-9 codes
Description
This is reasonably fast, but calculates all the minors, then throws away the result.
Usage
icd9GetMajor(icd9, isShort)
icd9GetMajorShort(icd9Short)
Arguments
icd9
is
a character vector or factor of ICD-9 codes. If fewer than five characters
is given in a code, then the digits are greedily assigned to hundreds, then
tens, then units, before the decimal parts. E.g. "10" becomes "010", not
"0010".
isShort
single logical value which determines whether the ICD-9 code
provided is in short (TRUE) or decimal (FALSE) form. Where reasonable, this
is guessed from the input data.