R help - May 2013 - combine two columns into one

Hey all!

I have a time series dataset like this:

Date    Time   Var
1            1        2
1           1        4
1           1         5
1          2          8
1          2          8
1         2           9
2        1            3
2        1              4
2        1            4

I created a unique id for each row:
dat$UniqueID <- paste(dat$Date,dat$Time, sep = '_')

then

aggregate(dat$Var, list(dat$UniqueID), sum)

however the final output is not in ideal order I look for (I simply this
example provided above).I would like to have order like this:

1_1
1_2
2_1

Thanks for your help!

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Hi,
May be I misunderstood your question:
dat<- read.table(text="
Date??? Time? Var
1??????????? 1??????? 2
1????????? 1??????? 4
1????????? 1??????? 5
1????????? 2????????? 8
1????????? 2????????? 8
1??????? 2????????? 9
2??????? 1??????????? 3
2??????? 1????????????? 4
2??????? 1??????????? 4
",sep="",header=TRUE)
dat$UniqueID <- paste(dat$Date,dat$Time, sep = '_')
?aggregate(dat$Var,list(dat$UniqueID),sum) #isn't this the correct order
#? Group.1? x
#1???? 1_1 11
#2???? 1_2 25
#3???? 2_1 11
library(plyr)
ddply(dat,.(UniqueID),summarize,Var=sum(Var))
#? UniqueID Var
#1????? 1_1? 11
#2????? 1_2? 25
#3????? 2_1? 11
A.K.



----- Original Message -----
From: Ye Lin <yelin at lbl.gov>
To: R help <r-help at r-project.org>
Cc: 
Sent: Wednesday, May 29, 2013 2:23 PM
Subject: [R] combine two columns into one

Hey all!

I have a time series dataset like this:

Date? ? Time?  Var
1? ? ? ? ? ? 1? ? ? ? 2
1? ? ? ? ?  1? ? ? ? 4
1? ? ? ? ?  1? ? ? ?  5
1? ? ? ? ? 2? ? ? ? ? 8
1? ? ? ? ? 2? ? ? ? ? 8
1? ? ? ?  2? ? ? ? ?  9
2? ? ? ? 1? ? ? ? ? ? 3
2? ? ? ? 1? ? ? ? ? ? ? 4
2? ? ? ? 1? ? ? ? ? ? 4

I created a unique id for each row:
dat$UniqueID <- paste(dat$Date,dat$Time, sep = '_')

then

aggregate(dat$Var, list(dat$UniqueID), sum)

however the final output is not in ideal order I look for (I simply this
example provided above).I would like to have order like this:

1_1
1_2
2_1

Thanks for your help!

??? [[alternative HTML version deleted]]

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