R dummies

NaN in calculations. The outcome of those calculations is always NaN, though, as yousee here:> NaN + 4[1] NaNYou can test whether a calculation results in NaN by using the is.nan()function. Note that both is.finite() and is.infinite() return FALSE when you’retesting on a NaN value.Dealing with missing valuesAs we mention earlier in this chapter, one of the most common problems instatistics is incomplete data sets. To deal with missing values, R uses the reservedkeyword NA, which stands for Not Available. You can use NA as a valid value, so youcan assign it as a value as well:> x x + 4[1] NA> log(x)[1] NAIf you want to test whether a value is NA, you can use the is.na() function, asfollows:> is.na(x)[1] TRUENote that the is.na() function also returns TRUE if the value is NaN. Thefunctions is.finite(), is.infinite(), and is.nan() return FALSE for NA values.Calculating infinite, undefined, and missing valuesTable 4-3 provides an overview of results from the functions described in the