5.2 Omitting missing values

If some observations have missing data (coded NA) on a given variable, summary statistic functions may yield an error. To ignore any missing values in carrying out calculations, include the argument na.rm=TRUE in the function.

  a = c(1,3,5,NA,7)

  mean(a) # Operation fails

## [1] NA

  mean(a, na.rm = TRUE) # Successfully calculates the mean

## [1] 4