[R] merge without NA last

[arun]

library(plyr)
 colnames(Y)[2]<- colnames(X)
 join(X,Y,type="left",by="k1")
#    k1 k2
#1    A  1
#2 <NA> NA
#3    C  3
#4    B  2
A.K.



----- Original Message -----
From: nevil amos <nevil.amos at gmail.com>
To: r-help <R-help at r-project.org>
Cc: 
Sent: Friday, May 31, 2013 4:07 AM
Subject: [R] merge without NA last

I am trying to create a merge where the first value contains NA values.  I
wish to retain these in order.  however when I use all.x=T and sort=F they
are retained but na values are placed last:

> X<-data.frame(k1=c("A",NA,"C","B"))
> print (X)
    k1
1    A
2 <NA>
3    C
4    B
> Y<-data.frame(k2=c(1,2,3),k3=c("A","B","C"))
> Z<-merge(X,Y, by.x=1,by.y=2,all.x=T,sort=F)
> print (Z)
    k1 k2
1    A  1
2    C  3
3    B  2
4 <NA> NA


The result I need is
    k1  k2
1    A  1
2 <NA> NA
3    C 3
4    B 2

how do I prevent NA c=values being sorted to last - I need to retain values
in position.

thanks

Nevil Amos

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