# Source code for featuretools.primitives.standard.aggregation.num_consecutive_less_mean

```
import numpy as np
from woodwork.column_schema import ColumnSchema
from woodwork.logical_types import IntegerNullable
from featuretools.primitives.base import AggregationPrimitive
[docs]class NumConsecutiveLessMean(AggregationPrimitive):
"""Determines the length of the longest subsequence below the mean.
Description:
Given a list of numbers, find the longest subsequence of numbers
smaller than the mean of the entire sequence. Return the length
of the longest subsequence.
Args:
skipna (bool): If this is False and any value in x is `NaN`, then
the result will be `NaN`. If True, `NaN` values are skipped.
Default is True.
Examples:
>>> num_consecutive_less_mean = NumConsecutiveLessMean()
>>> num_consecutive_less_mean([1, 2, 3, 4, 5, 6])
3.0
We can also control the way `NaN` values are handled.
>>> num_consecutive_less_mean = NumConsecutiveLessMean(skipna=False)
>>> num_consecutive_less_mean([1, 2, 3, 4, 5, 6, None])
nan
"""
name = "num_consecutive_less_mean"
input_types = [ColumnSchema(semantic_tags={"numeric"})]
return_type = ColumnSchema(logical_type=IntegerNullable, semantic_tags={"numeric"})
stack_on_self = False
default_value = 0
def get_function(self):
def num_consecutive_less_mean(x):
# check for NaN cases
if x.isnull().all():
return np.nan
if not self.skipna and x.isnull().values.any():
return np.nan
x_mean = x.mean()
# In some cases, the mean of x may be NaN
# (such as when x has both inf and -inf values)
if np.isnan(x.mean()):
return np.nan
# Find indices of points at or above mean
x = x.dropna().reset_index(drop=True)
above_mean_indices = x[x >= x_mean].index.to_series()
# If none of x is above the mean, return the length of x
if above_mean_indices.empty:
return len(x)
# Pad index with start/end values, in case the longest
# sequence occurs at the beginning or end of x
above_mean_indices[-1] = -1
above_mean_indices[len(x)] = len(x)
above_mean_indices = above_mean_indices.sort_index()
# Calculate gaps between points above mean
above_mean_indices_shifted = above_mean_indices.shift(1)
diffs = above_mean_indices - above_mean_indices_shifted
# Take biggest gap, and subtract 1 to get result
max_gap = (diffs).max() - 1
return max_gap
return num_consecutive_less_mean
```