Hi, According to ?which.min it returns the "index of the (first) minimum". So I would expect it to also return the first minimum when providing two identical extrema. But my minimal reproducible doesn't do so: data1a <- c(3.2,4.2) data1b <- c(3.1,4.1) data2a <- c(0.2,1.2) data2b <- c(4.2,5.2) data3aa <- data1a - data2a data3ba <- data1b - data2a data3ab <- data1a - data2b data3bb <- data1b - data2b print (data3aa) print (which.min (data3aa)) print (which.max (data3aa)) print (data3ba) print (which.min (data3ba)) print (which.max (data3ba)) print (data3ab) print (which.min (data3ab)) print (which.max (data3ab)) print (data3bb) print (which.min (data3bb)) print (which.max (data3bb)) results in: [1] 3 3 [1] 1 [1] 1 [1] 2.9 2.9 [1] 2 [1] 1 [1] -1 -1 [1] 1 [1] 1 [1] -1.1 -1.1 [1] 2 [1] 1 First of all which.max works as expected by always returning 1. But which.min only does so if the values don't contain fractions. And I get
identical (data3ba, c(2.9,2.9))
[1] FALSE Why is which.min not always returning 1 but which.max does? Mike