Day 0: mean, median, mode, weighted mean

: Day 0 note taking

This is just for practice, can make it much shorter with some packages like numpy, scipy.

array = [n1, n2 .... nN]

type(n) == int

N = len(array)

Mean:

sum( all N element in array) / N

Median: middle element in a sorted array.

If a number of N is even, then you have two elements in the middle of the array.

an average of those two elements is median.

if N%2 == 0:

median = (arr[int(N/2)-1]+arr[int(N/2)])/2

else:

median = arr[int(N/2)]

Mode: the most popular number

It means the element who have the highest frequency of occurrence in the array.

arr_set = sorted(set(arr))

mode = arr[0]

count = 0

for element in arr_set:

tmp = arr.count(element)

if tmp > count:

mode = element

count = tmp

xxx = [ an array of discrete numbes, x ]

www = [ an array of corresponding weights, w ]

N = number of elements in the arrays (# of x_arr elements == # of w_arr elements)

Weighted Mean: all sum(x, w) in the array /sum(w_arr)

xw = sum([x*y for x,y in zip(xxx,www)])

weighted_mean = (round(xw/sum(www),1))

hon9g