R help - Oct 2010 - Getting tripped up on NAs in trying to create new variable

Hello R help:

I have the following data:

a <- c(NA, 2, 2, 3, 2, NA)
b <- c(NA, NA, 3, NA, 1, 3)
df <- data.frame(a, b)
> df
   a  b
1 NA NA
2  2 NA
3  2  3
4  3 NA
5  2  1
6  NA 3

I want to create variable c such that if there is a 3 in either variable a
or variable b, variable c is 1(rows 3, 4 & 6 below).

If 3 not in a or b and a value appears in a or b, then c is 0(row 2 below).
If NA is present in both variables, c is NA (row 1 below).

   a  b   c
1 NA NA   NA
2  2 NA   0
3  2  3   1
4  3 NA   1
5  2  1   0
6  NA 3   1


I have tried various ifelse attempts but have not hit upon the correct
solution yet. For example,
the following syntax throws NA for row two instead of the hope for
"0".

test <- ifelse(is.na(df$a) & is.na(df$b), NA,
  ifelse((!is.na(df$a) | !is.na(df$b)) & ((df$a ==3 | df$b == 3)), 1,
0))
> test
NA NA  1  1  0  1

Any help much appreciated.
-- 
Gregory L. Blevins
Office 952 944-5743
Cell 612 251 0232
gregblev@gmail.com

	[[alternative HTML version deleted]]

Tena koe Greg

df$c <- 0
df[apply(df[,-3], 1, function(x) any(x %in% 3)), 3] <- 1
df[apply(df[,-3], 1, function(x) all(is.na(x))), 3] <- NA
df
   a  b  c
1 NA NA NA
2  2 NA  0
3  2  3  1
4  3 NA  1
5  2  1  0
6 NA  3  1

HTH ....

Peter Alspach
> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of Greg Blevins
> Sent: Monday, 18 October 2010 2:04 p.m.
> To: r-help at r-project.org
> Subject: [R] Getting tripped up on NAs in trying to create new variable
> 
> Hello R help:
> 
> I have the following data:
> 
> a <- c(NA, 2, 2, 3, 2, NA)
> b <- c(NA, NA, 3, NA, 1, 3)
> df <- data.frame(a, b)
> > df
>    a  b
> 1 NA NA
> 2  2 NA
> 3  2  3
> 4  3 NA
> 5  2  1
> 6  NA 3
> 
> I want to create variable c such that if there is a 3 in either
> variable a
> or variable b, variable c is 1(rows 3, 4 & 6 below).
> 
> If 3 not in a or b and a value appears in a or b, then c is 0(row 2
> below).
> If NA is present in both variables, c is NA (row 1 below).
> 
>    a  b   c
> 1 NA NA   NA
> 2  2 NA   0
> 3  2  3   1
> 4  3 NA   1
> 5  2  1   0
> 6  NA 3   1
> 
> 
> I have tried various ifelse attempts but have not hit upon the correct
> solution yet. For example,
> the following syntax throws NA for row two instead of the hope for
"0".
> 
> test <- ifelse(is.na(df$a) & is.na(df$b), NA,
>   ifelse((!is.na(df$a) | !is.na(df$b)) & ((df$a ==3 | df$b == 3)), 1,
> 0))
> > test
> NA NA  1  1  0  1
> 
> Any help much appreciated.
> --
> Gregory L. Blevins
> Office 952 944-5743
> Cell 612 251 0232
> gregblev at gmail.com
> 
> 	[[alternative HTML version deleted]]
> 
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-
> guide.html
> and provide commented, minimal, self-contained, reproducible code.
The contents of this e-mail are confidential and may be subject to legal
privilege.
 If you are not the intended recipient you must not use, disseminate, distribute
or
 reproduce all or any part of this e-mail or attachments.  If you have received
this
 e-mail in error, please notify the sender and delete all material pertaining to
this
 e-mail.  Any opinion or views expressed in this e-mail are those of the
individual
 sender and may not represent those of The New Zealand Institute for Plant and
 Food Research Limited.

On Sun, Oct 17, 2010 at 9:03 PM, Greg Blevins <gregblev at gmail.com>
wrote:
> Hello R help:
>
> I have the following data:
>
> a <- c(NA, 2, 2, 3, 2, NA)
> b <- c(NA, NA, 3, NA, 1, 3)
> df <- data.frame(a, b)
>> df
> ? a ?b
> 1 NA NA
> 2 ?2 NA
> 3 ?2 ?3
> 4 ?3 NA
> 5 ?2 ?1
> 6 ?NA 3
>
> I want to create variable c such that if there is a 3 in either variable a
> or variable b, variable c is 1(rows 3, 4 & 6 below).
>
> If 3 not in a or b and a value appears in a or b, then c is 0(row 2 below).
> If NA is present in both variables, c is NA (row 1 below).
>
> ? a ?b ? c
> 1 NA NA ? NA
> 2 ?2 NA ? 0
> 3 ?2 ?3 ? 1
> 4 ?3 NA ? 1
> 5 ?2 ?1 ? 0
> 6 ?NA 3 ? 1
>
>
> I have tried various ifelse attempts but have not hit upon the correct
> solution yet. For example,
> the following syntax throws NA for row two instead of the hope for
"0".

Try this:

transform(df, c = ifelse(is.na(a) & is.na(b), NA, a %in% 3 | b %in% 3) + 0)

-- 
Statistics & Software Consulting
GKX Group, GKX Associates Inc.
tel: 1-877-GKX-GROUP
email: ggrothendieck at gmail.com