A	B	C
1   5	4.25	4.5
2   3.5	4	2.5
3   3.25	4	4
4   4.25	4.5	2.25
5   1.5	4.5	3

> c(a=5, b=4.25, c=4.5)
  a   b   c
5.0 4.25 4.5

x[r,]

#Add your data
x<-structure(list(A = c(5, 3.5, 3.25, 4.25, 1.5), B = c(4.25, 4,
4, 4.5, 4.5), C = c(4.5, 2.5, 4, 2.25, 3)), .Names = c("A", "B",
"C"), class = "data.frame", row.names = c(NA, -5L))

#The vector your result should match
y<-c(A=5, B=4.25, C=4.5)

#Test that the items in the row match the vector you wanted
x[1,]==y

> d <- data.frame(a=1:3, b=4:6, c=7:9)

> d
  a b c
1 1 4 7
2 2 5 8
3 3 6 9

> d[1, ]
  a b c
1 1 4 7

> d[1, ]['a']
  a
1 1

x<-structure(list(A = c(5, 3.5, 3.25, 4.25, 1.5), B = c(4.25, 4,
4, 4.5, 4.5), C = c(4.5, 2.5, 4, 2.25, 3)), .Names = c("A", "B",
"C"), class = "data.frame", row.names = c(NA, -5L))
subset(x, A ==5 & b==4.25 && c==4.5)