R help - Jun 2005 - return NA

A<-c(1,2,NA,7,5)
B<-c(3,4,1,4,1)
C<-c(6,5,6,NA,9)
D<-c(8,7,4,6,2)
df1<-cbind(A,B,C,D)
for(i in seq(1,ncol(df1)-1, by=2)) {
   ifelse(df1[,i]=="NA",df1[,i+1]=="NA",df1[,] )  }


Tried several variations but none worked.  I wish to find any NA's in
column's 1 or 3 and change the numerical value to the right  of  the "
NA"'s .  In this case I wish to replace the 1 and 6 respectively with
"NA".
Any help would be appreciated.

You need to use is.na(df1[,i]) to test for NA.

Andy
> From: dscully at fd9ns01.okladot.state.ok.us
> 
> 
> 
> 
> 
> A<-c(1,2,NA,7,5)
> B<-c(3,4,1,4,1)
> C<-c(6,5,6,NA,9)
> D<-c(8,7,4,6,2)
> df1<-cbind(A,B,C,D)
> for(i in seq(1,ncol(df1)-1, by=2)) {
>    ifelse(df1[,i]=="NA",df1[,i+1]=="NA",df1[,] )  }
> 
> 
> Tried several variations but none worked.  I wish to find any NA's in
> column's 1 or 3 and change the numerical value to the right  of  the
"
> NA"'s .  In this case I wish to replace the 1 and 6 
> respectively with "NA".
> Any help would be appreciated.
> 
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide! 
> http://www.R-project.org/posting-guide.html
> 
> 
>

dscully at fd9ns01.okladot.state.ok.us wrote:
> 
> 
> 
> A<-c(1,2,NA,7,5)
> B<-c(3,4,1,4,1)
> C<-c(6,5,6,NA,9)
> D<-c(8,7,4,6,2)
> df1<-cbind(A,B,C,D)
> for(i in seq(1,ncol(df1)-1, by=2)) {
>    ifelse(df1[,i]=="NA",df1[,i+1]=="NA",df1[,] )  }
> 
> 
> Tried several variations but none worked.  I wish to find any NA's in
> column's 1 or 3 and change the numerical value to the right  of  the
"
> NA"'s .  In this case I wish to replace the 1 and 6 respectively
with "NA".
> Any help would be appreciated.
> 
I think you want ?is.na.

for(i in seq(1, ncol(df1) - 1, by = 2))
   df1[, i + 1] <- ifelse(is.na(df1[, i]), df1[, i], df1[, i + 1])

--sundar

Here is a way to do it without a loop that could save some time for a big
dataset.
> df1
      A B  C D
[1,]  1 3  6 8
[2,]  2 4  5 7
[3,] NA 1  6 4
[4,]  7 4 NA 6
[5,]  5 1  9 2
> df2<-cbind(0,ifelse(is.na(df1),NA,0))[,-ncol(df1)-1]
> df2
        A B  C
[1,] 0  0 0  0
[2,] 0  0 0  0
[3,] 0 NA 0  0
[4,] 0  0 0 NA
[5,] 0  0 0  0
> df3<-df1+df2
> df3
      A  B  C  D
[1,]  1  3  6  8
[2,]  2  4  5  7
[3,] NA NA  6  4
[4,]  7  4 NA NA
[5,]  5  1  9  2

-----Original Message-----
From: r-help-bounces at stat.math.ethz.ch
[mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of
dscully at fd9ns01.okladot.state.ok.us
Sent: June 29, 2005 3:50 PM
To: r-help at stat.math.ethz.ch
Subject: [R] return NA





A<-c(1,2,NA,7,5)
B<-c(3,4,1,4,1)
C<-c(6,5,6,NA,9)
D<-c(8,7,4,6,2)
df1<-cbind(A,B,C,D)
for(i in seq(1,ncol(df1)-1, by=2)) {
   ifelse(df1[,i]=="NA",df1[,i+1]=="NA",df1[,] )  }


Tried several variations but none worked.  I wish to find any NA's in
column's 1 or 3 and change the numerical value to the right  of  the "
NA"'s .  In this case I wish to replace the 1 and 6 respectively with
"NA".
Any help would be appreciated.

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