dasf questions

• R: calculate rank sum automatically
• R: change to the same character as the previous character in a string
• R: preserving 1-row / -column matrix [duplicate]
• R: return row and column numbers of matches in a data frame
• R: workaround for variable-width lookbehind
• R: (*SKIP)(*FAIL) for multiple patterns
• R: lookaround within lookaround

dasf answers