Finding median of list in Python
How do you find the median of a list in Python? The list can be of any size and the numbers are not guaranteed to be in any particular order.
If the list contains an even number of elements, the function should return the average of the middle two.
Here are some examples (sorted for display purposes):
median([1]) == 1
median([1, 1]) == 1
median([1, 1, 2, 4]) == 1.5
median([0, 2, 5, 6, 8, 9, 9]) == 6
median([0, 0, 0, 0, 4, 4, 6, 8]) == 2
Answer
Python 3.4 has statistics.median:
Return the median (middle value) of numeric data.
When the number of data points is odd, return the middle data point. When the number of data points is even, the median is interpolated by taking the average of the two middle values:
>>> median([1, 3, 5]) 3 >>> median([1, 3, 5, 7]) 4.0
Usage:
import statistics
items = [6, 1, 8, 2, 3]
statistics.median(items)
#>>> 3
It's pretty careful with types, too:
statistics.median(map(float, items))
#>>> 3.0
from decimal import Decimal
statistics.median(map(Decimal, items))
#>>> Decimal('3')