SAX2 Arguments - Aster Analytics

Teradata Aster® Analytics Foundation User GuideUpdate 2
Product
Aster Analytics
Release Number
7.00.02
Published
September 2017
Language
English (United States)
Last Update
2018-04-17
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B700-1022
lifecycle
previous
Product Category
Software
ValueColumns
Specifies the names of the input table columns that contain the time series data to be transformed.
TimeColumn
[Optional] Specifies the name of the input table column that contains the time axis of the data.
WindowType
[Optional] Determines how much data the function processes at one time:
  • 'global' (Default)

    The function computes the SAX code using a single mean and standard deviation for the entire data set.

  • 'sliding'

    The function recomputes the mean and standard deviation for a sliding window of the data set.

Output
[Optional] Determines how the function outputs the results:
  • 'string' (Default)

    The function outputs a list of SAX codes for each window.

  • 'bytes'

    The function outputs the list of SAX codes as compact byte arrays (which are not "human-readable").

  • 'bitmap'

    The function outputs a JSON representation of a SAX bitmap.

  • 'characters'

    The function outputs one character for each line.

Mean
[Optional][Single-input syntax only] Specifies the global mean values that the function uses to calculate the SAX code for every partition. A mean_value has the data type DOUBLE PRECISION.

If Mean specifies only one value and ValueColumns specifies multiple columns, the specified value applies to every value_column.

If Mean specifies multiple values, it must specify a value for each value_column. The nth mean_value corresponds to the nth value_column.

Tip: To specify a different global mean value for each partition, use the multiple-input syntax and put the values in the meanstats table.
Stdev
[Optional][Single-input syntax only] Specifies the global standard deviation values that the function uses to calculate the SAX code for every partition. A stdev_value has the data type DOUBLE PRECISION and its value must be greater than 0.

If Stdev specifies only one value and ValueColumns specifies multiple columns, the specified value applies to every value_column.

If Stdev specifies multiple values, it must specify a value for each value_column. The nth stdev_value corresponds to the nth value_column.

Tip: To specify a different global standard deviation value for each partition, use the multiple-input syntax and put the values in the stdevstats table.
WindowSize
[Required if WindowType is 'sliding', not allowed otherwise.] Specifies the size of the sliding window. The value must be an integer greater than 0.
OutputFrequency
[Optional] Specifies the number of data points that the window slides between successive outputs. The value must be an integer greater than 0. Default: 1.
WindowType value must be 'sliding' and Output value cannot be 'characters'. If WindowType is 'sliding' and Output value is 'characters', OutputFrequency is automatically set to the value of Window_Size, so that a single character is assigned to each time point. If the number of data points in the time series is not an integer multiple of the window size, the function ignores the leftover parts.
PointsPerSymbol
[Optional] Specifies the number of data points to be converted into one SAX symbol. Each value must be an integer greater than 0. Default: 1.
WindowType value must be 'global'.
SymbolsPerWindow
[Optional] Specifies the number of SAX symbols to be generated for each window. Each value must be an integer greater than 0. Default: window_size (the value of WindowSize).
WindowType value must be 'sliding'.
AlphabetSize
[Optional] Specifies the number of symbols in the SAX alphabet. The value must be an integer in the range [2, 20]. Default: 4.
BitmapLevel
[Optional] Specifies the number of consecutive symbols to be converted to one symbol on a bitmap. For bitmap level 1, the bitmap contains the symbols 'a', 'b', 'c', and so on; for bitmap level 2, the bitmap contains the symbols 'aa', 'ab', 'ac', and so on. The input value must be an integer in the range [1, 4]. Default: 2.
Output value must be 'bitmap'.
PrintCodeStats
[Optional] Specifies whether the function prints the mean and standard deviation. Default: 'false'.
Output value must be 'string'.
Accumulate
[Optional] Specifies the names of the input table columns that are to appear in the output table. For each sequence in the input table, SAX2 choose the value corresponding to the first time point in the sequence to output as the accumulate value.