UNIX for Dummies Questions & Answers

By definition, if there are an odd number of elements in a list, the median is the middle element in the (sorted) list. (So for dog, with the values in the 3rd field being 0, 3, and 4; 3 is the median.) If there are an even number of elements in a list, the median is the average of the middle two elements of the list. (So for cat, with the values in the 3rd field being 2 and 6, 4 is the median.)

OK, so the median is based on data we don't see, and we just pick the middle without regard to any order but the given one. But I still don't understand.

Code:

id   col2   col3  median
dog   0       0          3      
dog   1       4          3
dog   2       3          3
cat    0       2          4
cat    1       6          4

4 makes sense for cat, being (2+6)/2, but how does one get 3 for dog? That's the last element, not the middle. I wondered if maybe they were line numbers instead, but that doesn't make sense either.

The median is the middle element of the list after that list has been sorted.