Created
September 3, 2017 16:04
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A Python function to filter a list of values for outliers by using an interquartile filter
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import math | |
def filter_outliers(values: list) -> list: | |
array_length = len(values) | |
if array_length < 4: | |
return values | |
values.sort() | |
if (array_length % 4) == 0: | |
quarter = int(array_length / 4) | |
q1 = (1 / 2) * (values[quarter] + values[quarter + 1]) | |
q3 = (1 / 2) * (values[quarter * 3] + values[(quarter * 3) + 1]) | |
else: | |
q1 = values[math.floor(array_length / 4 + 1)] | |
q3 = values[math.ceil(array_length * (3 / 4) + 1)] | |
iqr = q3 - q1 | |
max_value = q3 + iqr * 1.5 | |
min_value = q1 - iqr * 1.5 | |
return list(x for x in values if max_value >= x >= min_value) |
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