Sampling Function Syntax Elements | Teradata Vantage - Sampling Syntax Elements - Teradata Vantage

Machine Learning Engine Analytic Function Reference
Product
Teradata Vantage
Release Number
9.02
9.01
2.0
1.3
Published
February 2022
Language
English (United States)
Last Update
2022-02-10
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B700-4003
lifecycle
previous
Product Category
Teradata Vantage™
SampleFraction
Specify one or more fractions to use in sampling the data. (Syntax options that do not use SampleFraction require ApproxSampleSize.)
If you specify only one fraction, then the function uses fraction for all strata defined by the sample conditions.
If you specify more than one fraction, then the function uses each fraction for sampling a particular stratum defined by the condition syntax elements.
For conditional sampling with variable sample sizes, specify one fraction for each condition that you specify with the Strata syntax element.
Seed
[Optional] Specify the random seed the algorithm uses for repeatable results. The seed must be a LONG value.
For repeatable results, use both the Seed and UniqueID syntax elements. For more information, see Nondeterministic Results and UniqueID Syntax Element.
Default: 0
ApproxSampleSize
[Optional] Specify one or more approximate sample sizes to use in sampling the data. (Syntax options that do not use ApproxSampleSize require SampleFraction.) Each sample size is approximate because the function maps the size to the sample fractions and then creates the sample data.
If you specify only one size, it represents the total sample size for the entire population. If you also specify the Strata syntax element, the function proportionally creates sample units for each stratum.
If you specify more than one size, then each size corresponds to a stratum, and the function uses each size to create sample units for the corresponding stratum.
For conditional sampling with variable approximate sample sizes, specify one size for each condition that you specify with the Strata syntax element.
StratumColumn
[Required for conditional sampling, disallowed otherwise.] Specify the name of the column that contains the sample conditions. If the function has only InputTable, stratum_column is in InputTable. If the function has both InputTable and SummaryTable, stratum_column is in SummaryTable.
Strata
[Required with StratumColumn.] Specify the sample conditions that appear in the stratum_column. If Strata specifies a condition that does not appear in stratum_column, the function returns an error.