[R] Factors and NaN
Lee, Chel Hee
chl948 at mail.usask.ca
Fri Dec 5 19:40:48 CET 2014
'NaN' is a reserved keyword that implies 'Not a number'. I see that you
use a character vector that includes 'NA' and 'NaN'. The former 'NA' is
considered as a missing value; however, the latter 'NaN' is considered
as a string 'NaN'. That's why three levels of 'NaN', 'no', 'yes' are
Function 'is.nan()' test if a numeric value is 'NaN'. Since you are
using a character vector, the result of using 'is.nan()' should be all
If you wish to make R understand 'NaN' as missing value, it would be a
good choice to use reserved keyword 'NA_character' as shown in the below:
> x <- factor(c("yes", "yes", "no", NA, "yes", "no", NA_character_))
 yes yes no <NA> yes no <NA>
Levels: no yes
 FALSE FALSE FALSE TRUE FALSE FALSE TRUE
I hope this helps.
Chel Hee Lee
On 12/5/2014 9:16 AM, Dinesh Chowdhary wrote:
>> x <- factor(c("yes", "yes", "no", NA, "yes", "no", NaN))
>  yes yes no <NA> yes no NaN
> Levels: NaN no yes
>  FALSE FALSE FALSE FALSE FALSE FALSE FALSE
>>From the above snippet can you notice that the "NaN" value is not logically
> identified in a vector? Can anyone elaborate on this?
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