I'm sorry but I see to be getting an error. 

> data.tmp <- aggregate(MyTo ~ Date + Hour, data = tUnitsort[, cols], max) Error in `[.default`(xj, i) : invalid subscript type 'builtin'




________________________________
 From: Rui Barradas [via R] <ml-node+s789695n4636372h9@n4.nabble.com>
To: jcrosbie <james@crosb.ie> 
Sent: Thursday, July 12, 2012 3:12 PM
Subject: Re: remove loop which compares row i to row i-1


Hello, 

I've not been following this thread but this seems ndependent from 
previous posts. Try the following. 



url <- "http://r.789695.n4.nabble.com/file/n4636337/BR3_2011_New.csv" 
tUnitsort <- read.csv(url, header=TRUE) 

cols <- sapply(c("Date", "Hour", "BlockNumber", "MyTo"), function(x) 
         grep(x, names(tUnitsort))) 

# This does it 
# Use full data.frame 'tUnitsort' if you want 
data.tmp <- aggregate(MyTo ~ Date + Hour, data = tUnitsort[, cols], max)
data.tmp <- merge(tUnitsort[, cols], data.tmp, by=c("Date", "Hour")) 

# Make it pretty 
idx <- grep("MyTo", names(data.tmp)) 
names(data.tmp)[idx] <- c("MyTo", "NewColumn") 

# See it 
head(data.tmp, 20) 
tail(data.tmp, 20) 


Also, you should quote the context. Many, almost all of us do NOT read 
the posts on Nabble. And Nabble does have a "quote" button. 

Hope this helps, 

Rui Barradas 

Em 12-07-2012 18:55, jcrosbie escreveu: 

> Thank you, 
> 
> I am sorry but I am still trying to figure out how to make the function 
> work. 
> 
> I have a column called tUnitsort$BlockNumber which can range from 0 to 6.
> I have another two columns with the date and the hour ending for the given 
> day. 
> Example 
> 
> Date        Hour   BlockNumber  MyTo  NewColumn 
> 2011-01   1          2                            140     140 
> 2011-01   1          1                           70        140 
> 2011-01   1          0                           0           140 
> 2011-02   1          2                           160     160 
> 2011-02   1          1                           70        160 
> 2011-02   1          0                           0          160 
> 2011-03   1          2                           150     150 
> 
> I want to create a NewColumn which will place the MyTo number for the 
> highest block number for the rest blocks in a given hour ending within a
> day. 
> 
> 
> ifelse(tUnitsort[,4]>=tUnitsort[-1,4],tUnitsort[,7],tUnitsort[-1,7]) 
> 
> I am unsure how to refference the element before in this case.  I thought 
> the -1 was doing this but I believe I'm wrong now. 
> 
> http://r.789695.n4.nabble.com/file/n4636337/BR3_2011_New.csv
> BR3_2011_New.csv 
> 
> -- 
> View this message in context: http://r.789695.n4.nabble.com/remove-loop-which-compares-row-i-to-row-i-1-tp4635327p4636337.html
> Sent from the R help mailing list archive at Nabble.com. 
> 
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