20.1.5 Median
Although the average of a list of numbers typically means the mean,
there are other notions of “average”. Another such notion is the
median; the median of a list of numbers is the middle number when they are
listed in numeric order. For example, the median of the list
[1,2,5,7,20] is simply 5. If the length of a list of numbers is
even, the median is the mean of the two middle numbers;
for example, the median of [1,2,5,7,20,21] is (5+7)/2=6.
The median function finds the median of a list.
-
median takes one mandatory argument and one optional
argument:
-
L, a list of numbers.
- Optionally, W, a list of positive integers for weights,
where the weight of number represents how many times it is counted in
a list.
- median(L ⟨,W⟩) returns the median of
the list.
Examples
| median([1,2,5,7,20],[5,3,2,1,2]) |
since the median of 1,1,1,1,1,2,2,2,5,5,7,20,20 is 2.