The two datasets below are excerpts from much larger datasets. Note that
there are duplicate dates in both dat1 and dat2, e.g., "2009-10-14".
dat1 <- read.table(textConnection("Date ConcAve
2009-07-08 7
2009-08-26 1
2009-08-26 2
2009-09-15 2
2009-10-14 2
2009-10-14 2
2009-10-16 101
2009-10-16 93
2009-11-18 4
2009-11-18 3
2010-01-04 4"),header=T)
closeAllConnections()
dat2 <- read.table(textConnection("Date ConcAve
2009-08-26 4.84e-05
2009-09-15 4.58e-05
2009-10-14 3.86e-05
2009-10-14 3.55e-05
2009-10-16 3.07e-05
2009-10-16 2.35e-05
2009-11-18 2.00e-05
2009-11-18 1.96e-05
2010-01-04 1.52e-05
2010-01-04 1.53e-05
2010-02-10 2.23e-05"),header=T)
closeAllConnections()
I'm seeking an R operation that will append a third column to both
data.frame's such that it makes these duplicates unique when I run merge().
The desired result for dat1 would be:
Date ConcAve item
2009-07-08 7 1
2009-08-26 1 1
2009-08-26 2 2
2009-09-15 2 1
2009-10-14 2 1
2009-10-14 2 2
2009-10-16 101 1
2009-10-16 93 2
2009-11-18 4 1
2009-11-18 3 2
2010-01-04 4 1
this way, I don't get this:
merge(dat1, dat2, by="Date")
# Date ConcAve.x ConcAve.y
#1 2009-08-26 1 4.84e-05
#2 2009-08-26 2 4.84e-05
#3 2009-09-15 2 4.58e-05
#4 2009-10-14 2 3.55e-05
#5 2009-10-14 2 3.86e-05
#6 2009-10-14 2 3.55e-05
#7 2009-10-14 2 3.86e-05
#8 2009-10-16 101 3.07e-05
#9 2009-10-16 101 2.35e-05
#10 2009-10-16 93 3.07e-05
#11 2009-10-16 93 2.35e-05
#12 2009-11-18 4 1.96e-05
#13 2009-11-18 4 2.00e-05
#14 2009-11-18 3 1.96e-05
#15 2009-11-18 3 2.00e-05
#16 2010-01-04 4 1.52e-05
#17 2010-01-04 4 1.53e-05
With the new column, which I've inserted manually in this small example, I
instead get the merge result below, which is what I'm after for the larger
problem:
dat3 <- read.table(textConnection("Date ConcAve item
2009-07-08 7 1
2009-08-26 1 1
2009-08-26 2 2
2009-09-15 2 1
2009-10-14 2 1
2009-10-14 2 2
2009-10-16 101 1
2009-10-16 93 2
2009-11-18 4 1
2009-11-18 3 2
2010-01-04 4 1"),header=T)
closeAllConnections()
dat4 <- read.table(textConnection("Date ConcAve item
2009-08-26 4.84e-05 1
2009-09-15 4.58e-05 1
2009-10-14 3.86e-05 1
2009-10-14 3.55e-05 2
2009-10-16 3.07e-05 1
2009-10-16 2.35e-05 2
2009-11-18 2.00e-05 1
2009-11-18 1.96e-05 2
2010-01-04 1.52e-05 1
2010-01-04 1.53e-05 2
2010-02-10 2.23e-05 1"),header=T)
closeAllConnections()
merge(dat3, dat4, by=c("Date","item"))
# Date item ConcAve.x ConcAve.y
#1 2009-08-26 1 1 4.84e-05
#2 2009-09-15 1 2 4.58e-05
#3 2009-10-14 1 2 3.86e-05
#4 2009-10-14 2 2 3.55e-05
#5 2009-10-16 1 101 3.07e-05
#6 2009-10-16 2 93 2.35e-05
#7 2009-11-18 1 4 2.00e-05
#8 2009-11-18 2 3 1.96e-05
#9 2010-01-04 1 4 1.52e-05
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