search for: 44azd

...e to use the sub twice, first extracting the first variable, then the second? The third example should return nothing, because it's inverted, but it returns the whole string. I know I could check that separately, but is there no better way? patid=c("ALAN334","AzD44","44AZD") txt =sub("([[:alpha:]]+)([[:digit:]])+","\\1",patid) num =sub("([[:alpha:]]+)([[:digit:]])+","\\2",patid) It would be nice if the following data frame would be returned: txt num ALAN 334 AzD 44 NA NA (or "", ""...