Codes for Replacing Special Values in R

• grep {base} Pattern Matching and Replacement. 

E.g., sub(“”, 0 ,dat)

• dat[dat==“”] = 0  # replace empty cell in dat as 0
• replace(x, list, values)

E.g., dat <- replace(dat, is.na(dat), 0)

• na.strings=c("","NA")  # replace empty cell as NA when importing data