[R] Help with "MERGE" gratefully accepted

[Andrew Stryker]

Briggs, Meredith M <Meredith.Briggs at team.telstra.com> wrote on 2005-Apr-15:
> 
> Hello

Hi,

> How do I use function 'MERGE" to combine the FILE A and FILE B below to make FILE C?
> 
> Thank you
> 
> 
> 
>  FILE A      
> 	140        151        167        	
> 	30.1         11.4       40     
> 
> FILE B
> 
>       	140       167      	
> 	5.7	 30.3
> 
> FILE C
> 
> 	140        151        167        	
> 	30.1         11.4      40   
> 	5.7	  NA	    30.3

Your problem is much easier to solve if the data are arranged
differently.  Say,

File A
	ID, VAR_A
	140, 30.1
	151, 11.4
	167, 40

File B
	ID, VAR_B
	140, 5.7
	167, 30.3

File C
	ID, VAR_C, VAR_D
	140, 30.1, 5.7
	151, 11.4, NA
	167, 40, 30.3


Those files can be read with read.csv into data frames.  A simple

	ab <- merge(fa, fb)

where fa is the data frame for file A and fb the same for file
B will put you have the way there.  Pay attention to the all.x and
all.y options.

I suspect there is a way to do the transposition in R.  However,
indexing records as rows and fields as columns is the standard
approach.  If you follow this convention, you will find that many
tools, not just R, are much more likely to work with you.

Good luck,

Andrew