R/check_element2.R

In yufree/xMSannotator: xMSannotator: R package for network based annotation of metabolomics data.

check_element2 <- function(curformula, elementname) {
    
    curformula <- as.character(curformula)
    strsplit_var <- strsplit(curformula, split = "")
    
    
    g3 <- gregexpr(curformula, pattern = paste(elementname, 
        "[0-9]*", sep = ""))
    
    regexp_len3 <- attr(g3[[1]], "match.length")
    
    if (regexp_len3 > 0) {
        
        if (regexp_len3 == 1) {
            numelement <- 1
            
        } else {
            numelement <- paste(strsplit_var[[1]][(g3[[1]][1] + 
                1):(g3[[1]][1] + regexp_len3 - 1)], collapse = "")
            
            numelement <- as.numeric(numelement)
            
        }
    } else {
        numelement <- 0
        
    }
    
    return(numelement)
}