ConstantDetection.md

Constant Detection

A collection of quality check routines to find constant values and plateaus.

Index

• constants_flagBasic
• constants_flagVarianceBased

constants_flagBasic

constants_flagBasic(window, thresh=0)

parameter	data type	default value	description
window	integer/offset string		The minimum count or duration in which the values must be constant to be considered as plateau candidates. See condition (1)
thresh	float	0	The maximum difference between values to still considered as constant. See condition (2)

This functions flags plateaus/series of constant values of length window if their difference is smaller than thresh.

A set of consecutive values x_n, ..., x_{n+k} of a time series x_t is considered to be constant, if:

1. k \ge window
2. |x_n - x_{n+s}| \le thresh, s \in {1,2, ..., k}

constants_flagVarianceBased

constants_flagVarianceBased(window="12h", thresh=0.0005,
                            max_missing=None, max_consec_missing=None)

parameter	data type	default value	description
window	offset string	12h	The minimum duration in which the values must be constant to be considered as plateau candidates. See condition (1)
thresh	float	0.0005	The maximum variance of a group of values, to still consider them as constant. See condition (2)
max_missing	integer	None	The maximum count of missing values that are allowed in the window. If not set, this condition is ignored and infinity missing values are allowed.
max_consec_missing	integer	None	The maximum count of consecutive missing values, that are allowed in the window. If not set, this condition is ignored and infinity consecutive missing values are allowed.

This function flags plateaus/series of constant values. Any set of consecutive values x_n,..., x_{n+k} of a timeseries x_t is flagged, if:

1. k \ge window
2. \sigma(x_n,..., x_{n+k}) \le thresh

NOTE:

• Only works for time series
• The time series is expected to be harmonized to an equidistant frequency grid
• When max_missing or max_consec_missing are set, plateaus not fulfilling the respective condition will not be flagged