[Solved] Matching a value in one column to the name of another column [closed]

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We can use row/column indexing to extract the elements from the first dataset and create the ‘result’ column in ‘d2’

d2$result <- d1[-1][cbind(1:nrow(d1), match(d2$mycol, names(d1)[-1]))]
d2
#  mycol result
#1     a     40
#2   bxb     88
#3   bxb     76
#4    ct     33

It could be also that there is a single dataset available i.e. ‘d1’ and want to get the ‘d2’. In that case, do a melt and subset

library(reshape2)
subset(melt(d1, id.var="mycol"), mycol==variable, select= c(1,3))

data

d1 <- data.frame(mycol = c("a", "bxb", "bxb", "ct"), a = c(40, 8, 43, 94), 
 `bxb` =c(7, 88, 76, 12), ct = c(4,6, 8954, 33), stringsAsFactors=FALSE, 
 check.names=FALSE) 
d2 <- data.frame(mycol = c('a', 'bxb', 'bxb', 'c'), stringsAsFactors=FALSE)

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solved Matching a value in one column to the name of another column [closed]