Package tech.tablesaw.aggregate

Class Summarizer

java.lang.Object
tech.tablesaw.aggregate.Summarizer
public class Summarizer extends Object
Summarizes the data in a table, by applying functions to a subset of its columns.

How to use:

1. Create an instance providing a source table, the column or columns to summarize, and a function or functions to apply 2. Applying the functions to the designated columns, possibly creating subgroup summaries using one of the by() methods

  • Constructor Summary

    Constructors
    Constructor
    Description
    Summarizer(Table sourceTable, List<String> columnNames, AggregateFunction<?,?>... functions)
    Returns an object capable of summarizing the given column in the given sourceTable, by applying the given functions
    Summarizer(Table sourceTable, Column<?> column, AggregateFunction<?,?>... functions)
    Returns an object capable of summarizing the given column in the given sourceTable, by applying the given functions
    Summarizer(Table sourceTable, Column<?> column1, Column<?> column2, AggregateFunction<?,?>... functions)
    Returns an object capable of summarizing the given columns in the given sourceTable, by applying the given functions
    Summarizer(Table sourceTable, Column<?> column1, Column<?> column2, Column<?> column3, AggregateFunction<?,?>... functions)
    Returns an object capable of summarizing the given column2 in the given sourceTable, by applying the given functions
    Summarizer(Table sourceTable, Column<?> column1, Column<?> column2, Column<?> column3, Column<?> column4, AggregateFunction<?,?>... functions)
    Returns an object capable of summarizing the given columns in the given sourceTable, by applying the given functions

  • Method Summary

    Modifier and Type
    Method
    Description
    Table
    apply()
    Returns the result of applying to the functions to all the values in the appropriate column TODO add a test that uses a non numeric return type with apply
    Table
    by(int step)
    Returns a summary of the records grouped into subsets of the same size, in the order they appear
    Table
    by(String... columnNames)
    Similar in intent to the SQL "group by" statement, it produces a table with one row for each subgroup of the output data containing the result of applying the summary functions to the subgroup
    Table
    by(CategoricalColumn<?>... columns)
    Similar in intent to the SQL "group by" statement, it produces a table with one row for each subgroup of the output data containing the result of applying the summary functions to the subgroup
    Summarizer
    groupBy(int step)
    TODO: research how the groupBy() methods differ from the by() methods?
    Summarizer
    groupBy(String... columnNames)
    TODO: research how the groupBy() methods differ from the by() methods?
    Summarizer
    groupBy(CategoricalColumn<?>... columns)
    TODO: research how the groupBy() methods differ from the by() methods?
    Table
    having(Function<Table,Selection> selection)
    Similar in intent to the SQL having command, it enables the user to apply a filter to the grouped results of summary.

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Constructor Details

    • Summarizer

      public Summarizer(Table sourceTable, Column<?> column, AggregateFunction<?,?>... functions)
      Returns an object capable of summarizing the given column in the given sourceTable, by applying the given functions

    • Summarizer

      public Summarizer(Table sourceTable, List<String> columnNames, AggregateFunction<?,?>... functions)
      Returns an object capable of summarizing the given column in the given sourceTable, by applying the given functions

    • Summarizer

      public Summarizer(Table sourceTable, Column<?> column1, Column<?> column2, AggregateFunction<?,?>... functions)
      Returns an object capable of summarizing the given columns in the given sourceTable, by applying the given functions

    • Summarizer

      public Summarizer(Table sourceTable, Column<?> column1, Column<?> column2, Column<?> column3, Column<?> column4, AggregateFunction<?,?>... functions)
      Returns an object capable of summarizing the given columns in the given sourceTable, by applying the given functions

    • Summarizer

      public Summarizer(Table sourceTable, Column<?> column1, Column<?> column2, Column<?> column3, AggregateFunction<?,?>... functions)
      Returns an object capable of summarizing the given column2 in the given sourceTable, by applying the given functions

  • Method Details

    • by

      public Table by(String... columnNames)
      Similar in intent to the SQL "group by" statement, it produces a table with one row for each subgroup of the output data containing the result of applying the summary functions to the subgroup
      Parameters:
      columnNames - The names of the columns to group on
      Returns:
      A table containing the grouped results

    • by

      public Table by(CategoricalColumn<?>... columns)
      Similar in intent to the SQL "group by" statement, it produces a table with one row for each subgroup of the output data containing the result of applying the summary functions to the subgroup
      Parameters:
      columns - The columns to group on
      Returns:
      A table containing the grouped results

    • by

      public Table by(int step)
      Returns a summary of the records grouped into subsets of the same size, in the order they appear

      All groups have the same number of records. If the final group has fewer than step records it is dropped.

      Parameters:
      step - the number or records to include in each group

    • apply

      public Table apply()
      Returns the result of applying to the functions to all the values in the appropriate column TODO add a test that uses a non numeric return type with apply

    • having

      public Table having(Function<Table,Selection> selection)
      Similar in intent to the SQL having command, it enables the user to apply a filter to the grouped results of summary. Only groups that pass the filter are included in the output.
      Parameters:
      selection - A Selection where each index provided refers to a row in the output table
      Returns:
      A table of filtered summarized data

    • groupBy

      public Summarizer groupBy(CategoricalColumn<?>... columns)
      TODO: research how the groupBy() methods differ from the by() methods? Are they synonyms?

    • groupBy

      public Summarizer groupBy(String... columnNames)
      TODO: research how the groupBy() methods differ from the by() methods? Are they synonyms?

    • groupBy

      public Summarizer groupBy(int step)
      TODO: research how the groupBy() methods differ from the by() methods? Are they synonyms?