subseting a data frame under a specific condition - r

Question

How can i get rows of a data frame that has a same value in a element of that comparing with another data frame ?
I have written this but it didn't work.
# example of two data frame
df1 <- data.frame(V1 = c("a", "g", "h", "l", "n", "e"), V2 = c("b", "n", "i", "m", "i", "f"), stringsAsFactors = F)
df2 <- data.frame(V1 = c("a", "c", "f","h"), V2 = c("b", "d", "e","z"), stringsAsFactors = F)
# finding joint values in each element of two data frames
res1<-intersect(df1$V1,df2$V1)
res2<-intersect(df1$V2,df2$V2)
res3<-intersect(df1$V1,df2$V2)
res4<-intersect(df1$V1,df2$V2)
# Getting rows that has joint value at least in one element of df1
ress1<-df1[apply(df1, MARGIN = 1, function(x) all(x== res1)), ]
ress2<-df1[apply(df1, MARGIN = 1, function(x) all(x== res2)), ]
ress3<-df1[apply(df1, MARGIN = 1, function(x) all(x== res3)), ]
ress4<-df1[apply(df1, MARGIN = 1, function(x) all(x== res4)), ]
# Getting rows that has joint value at least in one element of df2
resss1<-df2[apply(df2, MARGIN = 1, function(x) all(x== res1)), ]
resss2<-df2[apply(df2, MARGIN = 1, function(x) all(x== res2)), ]
resss3<-df2[apply(df2, MARGIN = 1, function(x) all(x== res3)), ]
resss4<-df2[apply(df2, MARGIN = 1, function(x) all(x== res4)), ]
# then combine above results
final.res<-rbind(ress1,ress2,ress3,ress4,resss1,resss2,resss3,resss4)
My favorite result is:
a b
h z
h i
f e
e f

Answer 1

This should work
#Import data
df1 <- data.frame(V1 = c("a", "g", "h", "l", "n", "e"), V2 = c("b", "n", "i", "m", "i", "f"), stringsAsFactors = F)
df2 <- data.frame(V1 = c("a", "c", "f","h"), V2 = c("b", "d", "e","z"), stringsAsFactors = F)
# Get the intersects
vals <- intersect(c(df1$V1, df1$V2), c(df2$V1, df2$V2))
#Get the subsets and rbind them
full <- rbind(
subset(df1, df1$V1 %in% vals),
subset(df1, df1$V2 %in% vals),
subset(df2, df2$V1 %in% vals),
subset(df2, df2$V2 %in% vals)
)
#Remove duplicates
full <- full[!duplicated(full),]