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NaN (“Not a Number”) means 0/0
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NA (“Not Available”) is generally interpreted as a missing value and has various forms – NA_integer_, NA_real_, etc.
- Therefore, NaN ≠ NA and there is a need for NaN and NA.
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is.na() returns TRUE for both NA and NaN, however is.nan() return TRUE for NaN (0/0) and FALSE for NA.
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NULL represents that the value in question simply does not exist, rather than being existent but unknown.
- REF:
- http://www.cookbook-r.com/Basics/Working_with_NULL_NA_and_NaN/
- http://*.com/questions/7031127/data-frames-and-is-nan
- http://www.r-bloggers.com/difference-between-na-and-nan-in-r/
- http://help.scilab.org/docs/5.5.2/en_US/isnan.html
- http://www.quantlego.com/howto/special-missing-values-in-r/
