harmonic.py

"""
Harmonic mean
Reference: https://en.wikipedia.org/wiki/Harmonic_mean

Harmonic series
Reference: https://en.wikipedia.org/wiki/Harmonic_series(mathematics)
"""


defis_harmonic_series(series: list) ->bool:
"""
 checking whether the input series is arithmetic series or not
 >>> is_harmonic_series([ 1, 2/3, 1/2, 2/5, 1/3])
 True
 >>> is_harmonic_series([ 1, 2/3, 2/5, 1/3])
 False
 >>> is_harmonic_series([1, 2, 3])
 False
 >>> is_harmonic_series([1/2, 1/3, 1/4])
 True
 >>> is_harmonic_series([2/5, 2/10, 2/15, 2/20, 2/25])
 True
 >>> is_harmonic_series(4)
 Traceback (most recent call last):
 ...
 ValueError: Input series is not valid, valid series - [1, 2/3, 2]
 >>> is_harmonic_series([])
 Traceback (most recent call last):
 ...
 ValueError: Input list must be a non empty list
 >>> is_harmonic_series([0])
 Traceback (most recent call last):
 ...
 ValueError: Input series cannot have 0 as an element
 >>> is_harmonic_series([1,2,0,6])
 Traceback (most recent call last):
 ...
 ValueError: Input series cannot have 0 as an element
 """
ifnotisinstance(series, list):
raiseValueError("Input series is not valid, valid series - [1, 2/3, 2]")
iflen(series) ==0:
raiseValueError("Input list must be a non empty list")
iflen(series) ==1andseries[0] !=0:
returnTrue
rec_series= []
series_len=len(series)
foriinrange(series_len):
ifseries[i] ==0:
raiseValueError("Input series cannot have 0 as an element")
rec_series.append(1/series[i])
common_diff=rec_series[1] -rec_series[0]
forindexinrange(2, series_len):
ifrec_series[index] -rec_series[index-1] !=common_diff:
returnFalse
returnTrue


defharmonic_mean(series: list) ->float:
"""
 return the harmonic mean of series

 >>> harmonic_mean([1, 4, 4])
 2.0
 >>> harmonic_mean([3, 6, 9, 12])
 5.759999999999999
 >>> harmonic_mean(4)
 Traceback (most recent call last):
 ...
 ValueError: Input series is not valid, valid series - [2, 4, 6]
 >>> harmonic_mean([1, 2, 3])
 1.6363636363636365
 >>> harmonic_mean([])
 Traceback (most recent call last):
 ...
 ValueError: Input list must be a non empty list

 """
ifnotisinstance(series, list):
raiseValueError("Input series is not valid, valid series - [2, 4, 6]")
iflen(series) ==0:
raiseValueError("Input list must be a non empty list")
answer=0
forvalinseries:
answer+=1/val
returnlen(series) /answer


if__name__=="__main__":
importdoctest

doctest.testmod()