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pythonlistaveragesublist
Mohammad
Mohammad

Reputation: 1013

How to calculate average of sub-lists based on Timestamp values

I have 2 lists. The 1st list is the Timestamps (sec) when data was measured. And 2nd list contains data.

I want to calculate the average of data every 10 sec. Note that timestamp between 2 consecutive data points is not fixed.

Example:

Timestamp = [2, 5, 8, 11, 18, 23, 25, 28]
Data = [1, 2, 3, 4, 5, 6, 7, 8]

And the expected output is supposed to be:

Output = [average of [1,2,3] , average of [4,5] , average of [6,7,8]]

I was wondering if there is any built-in function in Python like average-if analysis to do it automatically.

Thank you for your help.

Upvotes: 0

Views: 172

Answers (1)

Leo Arad
Leo Arad

Reputation: 4472

You can use for that the math function floor with defaultdict as

from collections import defaultdict
from math import floor

timestamp = [2, 5, 8, 11, 18, 23, 25, 28]
data = [1, 2, 3, 4, 5, 6, 7, 8]
average_dc= defaultdict(list)
for t, d in sorted(zip(timestamp, data), key=lambda x : x[0]):
     average_dc[math.floor(t / 10)].append(d)
averages = [sum(i)/ len(i) for i in average_dc.values()]

Output

[2.0, 4.5, 7.0]

The sorted(zip(timestamp, data), key=lambda x : x[0]) will concat the timestamp value with the value from data on the same index and then the for loop will insert to average_dc the relevant data value base on the related timestamp value.
In the last line, the list comprehension will iterate over each list in the average_dc and will calculate the average of it.

Upvotes: 1

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