[R] Handling NA values
smartpink111 at yahoo.com
Sat Feb 16 21:18:21 CET 2013
# 0 3 NA
----- Original Message -----
From: Christofer Bogaso <bogaso.christofer at gmail.com>
To: Marc Schwartz <marc_schwartz at me.com>
Cc: r-help <r-help at r-project.org>
Sent: Saturday, February 16, 2013 1:22 PM
Subject: Re: [R] Handling NA values
Thanks Marc for your reply.
However this leads to my problem of handling rowSums() function (hence
colSums()). Let take following matrix:
> Mat <- matrix(c(1, 1, NA, -1, 1, NA, NA, 1, NA), nc = 3)
[,1] [,2] [,3]
[1,] 1 -1 NA
[2,] 1 1 1
[3,] NA NA NA
> rowSums(Mat, na.rm = TRUE)
 0 3 0
I want to have some way to distinguish the 1st '0' and the 3rd '0'. I
want to see NA directly for the 3rd. Any possibility how to do that
through the rowSum() function?
Thanks and regards,
On Sat, Feb 16, 2013 at 11:52 PM, Marc Schwartz <marc_schwartz at me.com> wrote:
> On Feb 16, 2013, at 11:55 AM, Christofer Bogaso <bogaso.christofer at gmail.com> wrote:
>> Hello again,
>> I have a question on who sum() handle the NA values.
>>> sum(c(NA, 1), na.rm = TRUE)
>>  1
>> I understand this. However could not agree with following:
>>> sum(c(NA, NA), na.rm = TRUE)
>>  0
>> Where this '0' is coming from? Should not it be NA itself?
>> Thanks and regards,
> The result of:
> sum(c(NA, NA), na.rm = TRUE)
> is to sum an empty set, hence the 0.
>> na.omit(c(NA, NA))
>  1 2
>  "omit"
>  0
> If you retained the NA's, then the result is undefined:
>> sum(c(NA, NA))
>  NA
> for more information.
> Marc Schwartz
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