Averages/Arithmetic mean
You are encouraged to solve this task according to the task description, using any language you may know.
Write a program to find the mean (arithmetic average) of a numeric vector. The program should work on a zero-length vector (with an answer of 0).
J
mean=: +/ % #
That is, sum divided by the number of items. The verb also works on higher-ranked arrays. For example:
mean 3 1 4 1 5 9 3.83333 mean $0 NB. $0 is a zero-length vector 0 x=: 20 4 ?@$ 0 NB. a 20-by-4 table of random (0,1) numbers mean x 0.58243 0.402948 0.477066 0.511155
The computation can also be written as a loop. It is shown here for comparison only and is highly non-preferred compared to the version above.
mean1=: 3 : 0
z=. 0
for_i. i.#y do. z=. z+i{y end.
z % #y
)
mean1 3 1 4 1 5 9
3.83333
mean1 $0
0
mean1 x
0.58243 0.402948 0.477066 0.511155