Package dev.nm.misc.datastructure

Class MathTable

java.lang.Object
dev.nm.misc.datastructure.MathTable
public class MathTable extends Object
A mathematical table consists of numbers showing the results of calculation with varying arguments. It can be used to simplify and drastically speed up computation. We use them to archive results for, for example, quantiles of difficult distribution functions, often computed by slow Monte Carlo simulation.

This implementation provides various ways of looking up a table, esp. when an index is not exactly found in the table.

  • Constructor Details

    • MathTable

      public MathTable(String... headers)
      Constructs an empty table by headers.
      Parameters:
      headers - the column names; they must be unique

    • MathTable

      public MathTable(int nColumns)
      Constructs an empty table. The headers are given default names.
      Parameters:
      nColumns - the number of columns

  • Method Details

    • getHeaders

      public String[] getHeaders()
      Gets the column names.
      Returns:
      the headers

    • nColumns

      public int nColumns()
      Gets the number of columns in the table.
      Returns:
      the number of columns

    • addRow

      public void addRow(double index, double[] values)
      Adds a row to the table.
      Parameters:
      index - the row index
      values - the row values

    • addRows

      public void addRows(double[][] data)
      Adds rows by a double[][]. The first number in each row/double[] is the row index. For example, 
       new double[][]{
 {1.0, 1.1, 1.2, 1.3},
 {2.0, 2.1, 2.2, 2.3},
 {3.0, 3.1, 3.2, 3.3},
 {4.0, 4.1, 4.2, 4.3}
 };
      represents 
       1.0: {1.1, 1.2, 1.3}//row 1
 2.0: {2.1, 2.2, 2.3}//row 2
 3.0: {3.1, 3.2, 3.3}//row 3
 4.0: {4.1, 4.2, 4.3}//row 4
      Parameters:
      data - a double[][] of table entries.

    • getIndices

      public double[] getIndices()
      Gets a copy of the row indices.
      Returns:
      a copy of the row indices

    • getRowOnOrBefore

      public MathTable.Row getRowOnOrBefore(double i)
      Gets the row corresponding to a row index. If there is no row matching the exact index, the row with the biggest index but smaller than the specified index is returned.
      Parameters:
      i - a row index
      Returns:
      the corresponding row
      Throws:
      NoSuchElementException - if i is smaller than the first row index

    • getRowOnOrAfter

      public MathTable.Row getRowOnOrAfter(double i)
      Gets the row corresponding to a row index. If there is no row matching the exact value, the row with the smallest index value but bigger than the specified value is returned.
      Parameters:
      i - a row index
      Returns:
      the corresponding row
      Throws:
      NoSuchElementException - if i is bigger than the last row index value

    • getRowsOnOrBefore

      public Iterator<MathTable.Row> getRowsOnOrBefore(double i)
      Gets the rows having the row index value equal to or just smaller than i. The returned Iterator allows iterating the rows in reversed order starting from the matching row.
      Parameters:
      i - the row index
      Returns:
      an Iterator of Rows at or above the matching row

    • getRowsOnOrAfter

      public Iterator<MathTable.Row> getRowsOnOrAfter(double i)
      Gets the rows having the row index value equal to or just bigger than i. The returned Iterator allows iterating the rows starting from the matching row.
      Parameters:
      i - the row index
      Returns:
      an Iterator of Rows at or below the matching row

    • get

      public double get(double i, int j)
      Gets a particular table entry at [i,j]. If there is no matching row to i, by default, we use linear interpolation between the row above and below. If i is smaller than the first row index, we return the value at [1,j]. A subclass may override this behavior to customize interpolation.
      Parameters:
      i - a row index
      j - a column index, counting from 1
      Returns:
      the value at [i,j]
      Throws:
      NoSuchElementException - if rowValue is outside the table range

    • get

      public double get(double i, String header)
      Gets a particular table entry at [i, "header"]. If there is no matching row to i, by default, we use linear interpolation between the row above and below. If i is smaller than the first row index, we return the value at [1,"header"]. A subclass may override this behavior to customize interpolation.
      Parameters:
      i - a row value index
      header - the column name
      Returns:
      the value at [i, "header"]
      Throws:
      NoSuchElementException - if i is outside the table range