[R] Replacing null values

[Jeffrey Joh]

Sorry about the last message. I forgot to turn the HTML off.
I would like to reorder a table by column A, then fill column B with the values above it.  For example:
A   B
2   54
5   NA
8   78
4   NULL
3   26
9   NULL
 
First sort by column A:
A   B
2   54
3   26
4   NULL
5   NA
8   78
9   NULL
 
Then replace null/na values in column B with the value above it:
A   B
2      54
3   26
4   26
5   26
8   78
9   78

Jeff


> CC: r-help at r-project.org
> From: dwinsemius at comcast.net
> To: johjeffrey at hotmail.com
> Subject: Re: [R] Replacing null values
> Date: Sat, 30 Jul 2011 11:45:21 -0400
> 
> 
> On Jul 30, 2011, at 2:25 AM, Jeffrey Joh wrote:
> >
> > I would like to reorder a two-column table by column A, then fill  
> > column B with the values above it.  For example: Original:A   B2    
> > 545   NA8   784   NULL3   269   NULL First sort by column A:A      
> > B2     543     264     NULL5     NA8     789     NULL Then replace  
> > null/na values in column B with the value above it:A         
> > B2        543     264     265     268        789     78 What is the  
> > best way to do this?Jeff 		 	   		
> > 	[[alternative HTML version deleted]]
> 
> The "best way to do this" meaning to get help on _this_ mailing list,  
> is to post in plain text and to post the results of dput() on this  
> "two-column table".
> 
> All this is explained here:
> > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> > and provide commented, minimal, self-contained, reproducible code.
> 
> -- 
> 
> David Winsemius, MD
> West Hartford, CT
>