#Hello,

# I have a question about the addition of values in specific columns and
rows of a Data frame.
# Below I have created two data frames, X.df and "Y.df".

## creation of X.df data frame

X<- matrix(0,16,3)
X.df<-data.frame(X)
X.df[,1] <- c(1,1,1,1,2,2,2,2,3,3,3,3,4,4,4,4)
X.df[,2] <- c(1,2,3,4,1,2,3,4,1,2,3,4,1,2,3,4)
names(X.df)[1]<-"L(A)a(i)"
names(X.df)[2]<-"L(B)a(j)"
names(X.df)[3]<-"Counts"

X.df


## creation of Y.df data frame

Y<- matrix(0,7,3)
Y.df<-data.frame(Y)
Y.df[,1]<-c(1,3,4,2,2,1,2)
Y.df[,2]<-c(2,4,2,4,1,2,3)
Y.df[,3]<-c(1,2,1,0.5,1,1,1)
names(Y.df)[1]<-"L(A)a(i)"
names(Y.df)[2]<-"L(B)a(j)"
names(Y.df)[3]<-"Counts"

Y.df

# I would like to add the value in the "Counts" column of Y.df to the
"Counts" Column of X.df, based on matching
# the row value from the first two columns of each data.frame.  I have tried
the "merge" function but that
# doesn't give me the addition operation.

# here is what i would like the resulting operation to end up with in the
X.df data frame

X.df$Counts <- c(0,2,0,0,1,0,1,0.5,0,0,0,2,0,1,0,0)


X.df


# Any help or ideas would be greatly appreciated

# Thanks in advance

# Luke Neraas

# lukasneraas.r@gmail.com

# University of Alaska Fairbanks
# School of Fisheries and Ocean Sciences
# 11120 Glacier Highway
# UAF Fisheries Division
# Juneau, AK 99801

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