Util (ELKI: Environment for DeveLoping KDD-Applications Supported by Index-Structures)

java.lang.Object
- de.lmu.ifi.dbs.elki.utilities.Util

```
public final class Util
extends Object
```
This class collects various static helper methods. For helper methods related to special application fields see other utilities classes.

See Also:
de.lmu.ifi.dbs.elki.utilities

Nested Class Summary

Nested Classes
Modifier and Type Class and Description

static class Util.MaskedArrayList<T>
This class is a virtual collection based on masking an array list using a bit mask.

Nested Classes
Modifier and Type	Class and Description
`static class`	`Util.MaskedArrayList<T>` This class is a virtual collection based on masking an array list using a bit mask.

Constructor Summary

Constructors
Constructor and Description

Util()

Constructors
Constructor and Description
`Util()`

Method Summary

Methods
Modifier and Type	Method and Description
`static <O> void`	`addToList(List<O> list, O[] array)` Adds the entries of the specified array to the end of the given list.
`static int`	`arrayFind(String[] arr, Object ref)` Search an (unsorted) array linearly for an object.
`static List<Integer>`	`convertBitSetToListInt(BitSet b, int off)` Convert a bit set to a list of integers, representing bits that are set
`static double[]`	`convertToDoubles(float[] values)` Converts the specified array of doubles to an array of floats.
`static double[]`	`convertToDoubles(List<Double> values)` Converts the specified list of Double objects to an array of doubles.
`static float[]`	`convertToFloat(double[] values)` Converts the specified array of doubles to an array of floats.
`static List<Float>`	`convertToFloat(List<Double> values)` Converts the specified list of double objects to a list of float objects.
`static double[]`	`copy(double[] array)` Returns a new double array containing the same objects as are contained in the given array.
`static String[]`	`copy(String[] array)` Returns a new String array containing the same objects as are contained in the given array.
`static String`	`getFilePrefix(String fileName)` Returns the prefix of the specified fileName (i.e. the name of the file without extension).
`static int`	`getIndexOfMaximum(double[] values)` Returns the index of the maximum of the given values.
`static int`	`indexOfNthSetBit(BitSet bitset, int nthSetBit)` Returns the index of the n^th set bit in the given BitSet.
`static BitSet`	`int2Bit(int n)` Converts the specified positive integer value into a bit representation, where bit 0 denotes 2⁰, bit 1 denotes 2¹ etc.
`static <O> void`	`intersection(Set<O> s1, Set<O> s2, Set<O> result)` Provides the intersection of the two specified sets in the given result set.
`static String[]`	`joinArray(String[] array1, String[] array2)` Joins the specified arrays.
`static int`	`mixHashCodes(int... hash)` Mix multiple hashcodes into one.
`static BitSet`	`parseBitSet(char[] s)` Returns a new `BitSet` initialized to the values represented by the specified `char` array only containing '0' and '1' values.
`static BitSet`	`parseBitSet(String s)` Returns a new `BitSet` initialized to the values represented by the specified `String` only containing 0 and 1 values.
`static double[]`	`parseDoubles(String s)` Returns a new `Double` array initialized to the values represented by the specified `String` and separated by comma, as performed by the `valueOf` method of class `Double`.
`static float[]`	`parseFloats(String s)` Returns a new `Float` array initialized to the values represented by the specified `String` and separated by comma, as performed by the `valueOf` method of class `Float`.
`static String`	`parseSelectedBits(BitSet b, String sep)` Returns a string that represents the selected bits of the specified `BitSet`, while the first bit starts with 1.
`static <O> void`	`print(List<O> list, String separator, PrintStream out)` Prints the given list to the specified PrintStream.
`static DoubleVector`	`project(DoubleVector v, BitSet selectedAttributes)` Provides a new DoubleVector as a projection on the specified attributes.
`static SparseFloatVector`	`project(SparseFloatVector v, BitSet selectedAttributes)` Provides a new SparseFloatVector as a projection on the specified attributes.
`static BitSet`	`randomBitSet(int cardinality, int capacity, Random random)` Creates a new BitSet of fixed cardinality with randomly set bits.
`static double[]`	`unbox(Double[] array)` Returns the unboxed double array of the given Object Double array.
`static double[]`	`unbox(Number[] array)` Returns the unboxed double array of the given Object Number array.
`static float[]`	`unboxToFloat(Number[] array)` Returns the unboxed float array of the given Object Number array.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - Util
```
public Util()
```
- Method Detail
  - getFilePrefix
```
public static String getFilePrefix(String fileName)
```
    Returns the prefix of the specified fileName (i.e. the name of the file without extension).
    
    Parameters:
    fileName - the name of the file
    
    Returns:
    the prefix of the specified fileName
  - copy
```
public static String[] copy(String[] array)
```
    Returns a new String array containing the same objects as are contained in the given array.
    
    Parameters:
    array - an array to copy
    
    Returns:
    the copied array
  - copy
```
public static double[] copy(double[] array)
```
    Returns a new double array containing the same objects as are contained in the given array.
    
    Parameters:
    array - an array to copy
    
    Returns:
    the copied array
  - unbox
```
public static double[] unbox(Double[] array)
```
    Returns the unboxed double array of the given Object Double array.
    
    Parameters:
    array - the array to be unboxed
    
    Returns:
    the unboxed double array
  - unbox
```
public static double[] unbox(Number[] array)
```
    Returns the unboxed double array of the given Object Number array.
    
    Parameters:
    array - the array to be unboxed
    
    Returns:
    the unboxed double array
  - unboxToFloat
```
public static float[] unboxToFloat(Number[] array)
```
    Returns the unboxed float array of the given Object Number array.
    
    Parameters:
    array - the array to be unboxed
    
    Returns:
    the unboxed float array
  - parseDoubles
```
public static double[] parseDoubles(String s)
```
    Returns a new Double array initialized to the values represented by the specified String and separated by comma, as performed by the valueOf method of class Double.
    
    Parameters:
    s - the string to be parsed.
    
    Returns:
    a new Double array represented by s
  - parseFloats
```
public static float[] parseFloats(String s)
```
    Returns a new Float array initialized to the values represented by the specified String and separated by comma, as performed by the valueOf method of class Float.
    
    Parameters:
    s - the string to be parsed.
    
    Returns:
    a new Float array represented by s
  - convertToFloat
```
public static List<Float> convertToFloat(List<Double> values)
```
    Converts the specified list of double objects to a list of float objects.
    
    Parameters:
    values - the list of double objects to be converted
    
    Returns:
    the converted list of float objects
  - convertToFloat
```
public static float[] convertToFloat(double[] values)
```
    Converts the specified array of doubles to an array of floats.
    
    Parameters:
    values - the array of doubles to be converted
    
    Returns:
    the converted array of floats
  - convertToDoubles
```
public static double[] convertToDoubles(float[] values)
```
    Converts the specified array of doubles to an array of floats.
    
    Parameters:
    values - the array of doubles to be converted
    
    Returns:
    the converted array of floats
  - convertToDoubles
```
public static double[] convertToDoubles(List<Double> values)
```
    Converts the specified list of Double objects to an array of doubles.
    
    Parameters:
    values - the list of Double objects to be converted
    
    Returns:
    the converted array of doubles
  - print
```
public static <O> void print(List<O> list,
             String separator,
             PrintStream out)
```
    Prints the given list to the specified PrintStream. The list entries are separated by the specified separator. The last entry is not followed by a separator. Thus, if a newline is used as separator, it might make sense to print a newline to the PrintStream after calling this method.
    
    Type Parameters:
    O - object class
    Parameters:
    list - the list to be printed
    separator - the separator to separate entries of the list
    out - the target PrintStream
  - getIndexOfMaximum
```
public static int getIndexOfMaximum(double[] values)
                             throws ArrayIndexOutOfBoundsException
```
    Returns the index of the maximum of the given values. If no value is bigger than the first, the index of the first entry is returned.
    
    Parameters:
    values - the values to find the index of the maximum
    
    Returns:
    the index of the maximum in the given values
    
    Throws:
    
    ArrayIndexOutOfBoundsException - if values.length==0
  - parseBitSet
```
public static BitSet parseBitSet(String s)
```
    Returns a new BitSet initialized to the values represented by the specified String only containing 0 and 1 values.
    
    Parameters:
    s - the string to be parsed.
    
    Returns:
    a new BitSet represented by s
  - parseBitSet
```
public static BitSet parseBitSet(char[] s)
```
    Returns a new BitSet initialized to the values represented by the specified char array only containing '0' and '1' values.
    
    Parameters:
    s - the char array to be parsed.
    
    Returns:
    a new BitSet represented by s
  - parseSelectedBits
```
public static String parseSelectedBits(BitSet b,
                       String sep)
```
    Returns a string that represents the selected bits of the specified BitSet, while the first bit starts with 1. The selected bits are separated by the specified separator sep. If sep is ",", the result is suitable as a parameter for an IntListParameter.
    
    Parameters:
    b - the bit set to be parsed
    sep - the separator
    
    Returns:
    a string representing the selected bits of the specified BitSet
  - convertBitSetToListInt
```
public static List<Integer> convertBitSetToListInt(BitSet b,
                                   int off)
```
    Convert a bit set to a list of integers, representing bits that are set
    
    Parameters:
    b - Bitset
    off - Offset, set to 0 to start counting at 0, 1 to start counting at 1.
    
    Returns:
    List
  - randomBitSet
```
public static BitSet randomBitSet(int cardinality,
                  int capacity,
                  Random random)
```
    Creates a new BitSet of fixed cardinality with randomly set bits.
    
    Parameters:
    cardinality - the cardinality of the BitSet to create
    capacity - the capacity of the BitSet to create - the randomly generated indices of the bits set to true will be uniformly distributed between 0 (inclusive) and capacity (exclusive)
    random - a Random Object to create the sequence of indices set to true - the same number occurring twice or more is ignored but the already selected bit remains true
    
    Returns:
    a new BitSet with randomly set bits
  - project
```
public static DoubleVector project(DoubleVector v,
                   BitSet selectedAttributes)
```
    Provides a new DoubleVector as a projection on the specified attributes. If the given DoubleVector has already an ID not null, the same ID is set in the returned new DoubleVector. Nevertheless, the returned DoubleVector is not backed by the given DoubleVector, i.e., any changes affecting v after calling this method will not affect the newly returned DoubleVector.
    
    Parameters:
    v - a DoubleVector to project
    selectedAttributes - the attributes selected for projection
    
    Returns:
    a new DoubleVector as a projection on the specified attributes
    
    Throws:
    
    IllegalArgumentException - if the given selected attributes specify an attribute as selected which is out of range for the given DoubleVector.
    See Also:
    DoubleVector.doubleValue(int)
  - project
```
public static SparseFloatVector project(SparseFloatVector v,
                        BitSet selectedAttributes)
```
    Provides a new SparseFloatVector as a projection on the specified attributes. If the given SparseFloatVector has already an ID not null, the same ID is set in the returned new SparseFloatVector. Nevertheless, the returned SparseFloatVector is not backed by the given SparseFloatVector, i.e., any changes affecting v after calling this method will not affect the newly returned SparseFloatVector.
    
    Parameters:
    v - a SparseFloatVector to project
    selectedAttributes - the attributes selected for projection
    
    Returns:
    a new SparseFloatVector as a projection on the specified attributes
    
    Throws:
    
    IllegalArgumentException - if the given selected attributes specify an attribute as selected which is out of range for the given SparseFloatVector.
  - indexOfNthSetBit
```
public static int indexOfNthSetBit(BitSet bitset,
                   int nthSetBit)
                            throws IllegalArgumentException
```
    Returns the index of the n^th set bit in the given BitSet. For the parameter nthSetBit, following condition is assumed: 1 ≤ nthSetBit ≤ bitset.cardinality(). Otherwise, i.e., if the Bitset contains less than nthSetBit set bits or nthSetBit is not a positive number, the method throws an IllegalArgumentException. The worstcase runtime complexity of this method is in O( bitset.cardinality()).
    
    Parameters:
    bitset - the BitSet to derive the index of the n^th set bit in
    nthSetBit - which set bit to derive the index of
    
    Returns:
    the index of the n^th set bit in the given BitSet
    
    Throws:
    
    IllegalArgumentException - if the Bitset contains less than nthSetBit set bits or nthSetBit is not a positive number
  - intersection
```
public static <O> void intersection(Set<O> s1,
                    Set<O> s2,
                    Set<O> result)
```
    Provides the intersection of the two specified sets in the given result set.
    
    Type Parameters:
    O - object class
    Parameters:
    s1 - the first set
    s2 - the second set
    result - the result set
  - int2Bit
```
public static BitSet int2Bit(int n)
```
    Converts the specified positive integer value into a bit representation, where bit 0 denotes 2⁰, bit 1 denotes 2¹ etc.
    
    Parameters:
    n - the positive integer value to be converted
    
    Returns:
    the specified integer value into a bit representation
  - joinArray
```
public static String[] joinArray(String[] array1,
                 String[] array2)
```
    Joins the specified arrays.
    
    Parameters:
    array1 - the first array
    array2 - the second array
    
    Returns:
    a new array containing the entries of array1 and the array2.
  - addToList
```
public static <O> void addToList(List<O> list,
                 O[] array)
```
    Adds the entries of the specified array to the end of the given list.
    
    Type Parameters:
    O - object class
    Parameters:
    list - the list
    array - the array containing the objects to be added to the list
  - arrayFind
```
public static int arrayFind(String[] arr,
            Object ref)
```
    Search an (unsorted) array linearly for an object.
    
    Parameters:
    arr - Array to search
    ref - Object to search for
    
    Returns:
    Index of object or -1 if not found.
  - mixHashCodes
```
public static final int mixHashCodes(int... hash)
```
    Mix multiple hashcodes into one.
    
    Parameters:
    hash - Hashcodes to mix
    
    Returns:
    Mixed hash code

Class Util

Nested Class Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

Util

Method Detail

getFilePrefix

copy

copy

unbox

unbox

unboxToFloat

parseDoubles

parseFloats

convertToFloat

convertToFloat

convertToDoubles

convertToDoubles

print

getIndexOfMaximum

parseBitSet

parseBitSet

parseSelectedBits

convertBitSetToListInt

randomBitSet

project

project

indexOfNthSetBit

intersection

int2Bit

joinArray

addToList

arrayFind

mixHashCodes