Wrapper for the C function "join_gnps"
Arguments
- x
- Numeric vector or matrix for query masses. 
- y
- Numeric vector or matrix for target masses. 
- xPrecursorMz
- Numeric vector of precursor values for queries. 
- yPrecursorMz
- Numeric vector of precursor values for targets. 
- tolerance
- Numeric value specifying the tolerance in daltons. 
- ppm
- Numeric value specifying the tolerance in ppm.