[R] Missing values

[Stephen Liu]

----- Original Message ----

From: Robert Baer <rbaer at atsu.edu>
To: Stephen Liu <satimis at yahoo.com>; r-help at r-project.org
Sent: Wed, August 18, 2010 2:43:27 AM
Subject: Re: [R] Missing values


Hi Robert,


- snip -

>> z <- c(1:3,NA);  ind <- is.na(z)

># To see the logical vector the same size as the original print them out
># z has four elements, one of which is "not available" or "not applicable"
>z
>  [1]  1  2  3 NA
>
># ind has four LOGICAL elements, the last of which is "not available"
>#  so the function is.na() returns TRUE
>ind  # logical elements
>[1] FALSE FALSE FALSE  TRUE

Now I understand.  Thanks


- snip -

>>NaN means that the value wasn't missing but can't be expressed as a
>>number. 0/0 is NaN because the result is mathematically undefined

> # Are you reading zero divided by zero in the line above?

I read it as "OR".  It should be "division/divide" ?


>> Inf - Inf
> # infinity and minus infinity

I see.  It is "minus" sign NOT "to"


B.R.
Stephen L