trend_test

hana_ml.algorithms.pal.tsa.trend_test.trend_test(data, key=None, endog=None, method=None, alpha=None)

Trend test is a statistical method used in time series analysis to determine whether there is a consistent upward or downward movement over time, and calculate the de-trended time series.

Parameters:
dataDataFrame

The input data should comprise at least two columns. One is ID column, while the other is raw data.

keystr, optional

The ID column.

Defaults to the first column of data if the index column of data is not provided. Otherwise, defaults to the index column of data.

endogstr, optional

The column of series to be tested.

Defaults to the first non-ID column.

method{'mk', 'difference-sign'}, optional

Specifies the method used to identify the trend:

-'mk': Mann-Kendall test. -'difference-sign': Difference-sign test.

Defaults to 'mk'.

alphafloat, optional

The significance value.

Its typical value ranges between 0 and 0.5, asserting confidence in the observed trend within the series.

Defaults to 0.05.

Returns:
DataFrames

DataFrame 1 : statistics, structured as follows:

STAT_NAME: includes

  • TREND: -1 for downward trend, 0 for no trend, and 1 for upward trend

  • S: the number of positive pairs minus the negative pairs

  • P-VALUE: The p-value of the observed S

STAT_VALUE: value of stats above.

DataFrame 2 : a detrended table, structured as follows:

  • ID : Time stamp that is monotonically increasing sorted.

  • DETRENDED_SERIES: The corresponding de-trended time series. The first value absents if trend presents.

Examples

>>> stats, detrended = trend_test(data=df, key='ID', endog='SERIES', method='mk', alpha=0.05)
>>> stats.collect()
>>> detrended.collect()