This function checks if a string is a valid inchikey.
Inchikey must fulfill the following criteria:
1) consist of 27 characters;
2) be all uppercase, all letters (no numbers);
3) contain two hyphens at positions 15 and 26;
4) 24th character (flag character) be 'S' (Standard InChI) or 'N' (non-standard)
5) 25th character (version character) must be 'A' (currently).
Usage
is.inchikey(x, type = c("format", "chemspider"), verbose = TRUE)
Arguments
x
character; input InChIKey
type
character; How should be checked? Either, by format (see above) ('format') or by ChemSpider ('chemspider').
verbose
logical; print messages during processing to console?