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java.lang.Objectorg.apache.mahout.math.Partitioning
@Deprecated public class Partitioning
Field Summary | |
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protected static int |
steps
Deprecated. |
Method Summary | |
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static int |
dualPartition(double[] list,
double[] secondary,
int from,
int to,
double splitter)
Deprecated. Same as dualPartition(int[],int[],int,int,int) except that it synchronously partitions
double[] rather than int[] arrays. |
static void |
dualPartition(double[] list,
double[] secondary,
int from,
int to,
double[] splitters,
int splitFrom,
int splitTo,
int[] splitIndexes)
Deprecated. Same as dualPartition(int[],int[],int,int,int[],int,int,int[]) except that it synchronously
partitions double[] rather than int[] arrays. |
static int |
dualPartition(int[] list,
int[] secondary,
int from,
int to,
int splitter)
Deprecated. Same as partition(int[],int,int,int) except that this method synchronously partitions two arrays at
the same time; both arrays are partially sorted according to the elements of the primary array. |
static void |
dualPartition(int[] list,
int[] secondary,
int from,
int to,
int[] splitters,
int splitFrom,
int splitTo,
int[] splitIndexes)
Deprecated. Same as partition(int[],int,int,int[],int,int,int[]) except that this method synchronously
partitions two arrays at the same time; both arrays are partially sorted according to the elements of the primary
array. |
static void |
genericPartition(int from,
int to,
int splitFrom,
int splitTo,
int[] splitIndexes,
IntComparator comp,
IntComparator comp2,
IntComparator comp3,
Swapper swapper)
Deprecated. Same as partition(int[],int,int,int[],int,int,int[]) except that it generically partitions
arbitrary shaped data (for example matrices or multiple arrays) rather than int[] arrays. |
static int |
partition(double[] list,
int from,
int to,
double splitter)
Deprecated. Same as partition(int[],int,int,int) except that it partitions double[] rather than
int[] arrays. |
static void |
partition(double[] list,
int from,
int to,
double[] splitters,
int splitFrom,
int splitTo,
int[] splitIndexes)
Deprecated. Same as partition(int[],int,int,int[],int,int,int[]) except that it partitions double[] rather
than int[] arrays. |
static void |
partition(DoubleArrayList list,
int from,
int to,
DoubleArrayList splitters,
IntArrayList splitIndexes)
Deprecated. Equivalent to partition(list.elements(), from, to, splitters.elements(), 0, splitters.size()-1, splitIndexes.elements()). |
static int |
partition(int[] list,
int from,
int to,
int splitter)
Deprecated. Partitions (partially sorts) the given list such that all elements falling into the given interval are placed next to each other. |
static void |
partition(int[] list,
int from,
int to,
int[] splitters,
int splitFrom,
int splitTo,
int[] splitIndexes)
Deprecated. Partitions (partially sorts) the given list such that all elements falling into some intervals are placed next to each other. |
static void |
partition(IntArrayList list,
int from,
int to,
IntArrayList splitters,
IntArrayList splitIndexes)
Deprecated. Equivalent to partition(list.elements(), from, to, splitters.elements(), 0, splitters.size()-1, splitIndexes.elements()). |
static void |
partition(java.lang.Object[] list,
int from,
int to,
java.lang.Object[] splitters,
int splitFrom,
int splitTo,
int[] splitIndexes,
java.util.Comparator<java.lang.Object> comp)
Deprecated. Same as partition(int[],int,int,int[],int,int,int[]) except that it partitions Object[] rather
than int[] arrays. |
static int |
partition(java.lang.Object[] list,
int from,
int to,
java.lang.Object splitter,
java.util.Comparator<java.lang.Object> comp)
Deprecated. Same as partition(int[],int,int,int) except that it synchronously partitions the objects of the
given list by the order of the given comparator. |
static int |
triplePartition(double[] list,
double[] secondary,
double[] tertiary,
int from,
int to,
double splitter)
Deprecated. Same as triplePartition(int[],int[],int[],int,int,int) except that it synchronously partitions
double[] rather than int[] arrays. |
static void |
triplePartition(double[] list,
double[] secondary,
double[] tertiary,
int from,
int to,
double[] splitters,
int splitFrom,
int splitTo,
int[] splitIndexes)
Deprecated. Same as triplePartition(int[],int[],int[],int,int,int[],int,int,int[]) except that it synchronously
partitions double[] rather than int[] arrays. |
static int |
triplePartition(int[] list,
int[] secondary,
int[] tertiary,
int from,
int to,
int splitter)
Deprecated. Same as partition(int[],int,int,int) except that this method synchronously partitions three arrays
at the same time; all three arrays are partially sorted according to the elements of the primary array. |
static void |
triplePartition(int[] list,
int[] secondary,
int[] tertiary,
int from,
int to,
int[] splitters,
int splitFrom,
int splitTo,
int[] splitIndexes)
Deprecated. Same as partition(int[],int,int,int[],int,int,int[]) except that this method synchronously
partitions three arrays at the same time; all three arrays are partially sorted according to the elements of the
primary array. |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Field Detail |
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protected static int steps
Method Detail |
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public static void dualPartition(double[] list, double[] secondary, int from, int to, double[] splitters, int splitFrom, int splitTo, int[] splitIndexes)
dualPartition(int[],int[],int,int,int[],int,int,int[])
except that it synchronously
partitions double[] rather than int[] arrays.
public static int dualPartition(double[] list, double[] secondary, int from, int to, double splitter)
dualPartition(int[],int[],int,int,int)
except that it synchronously partitions
double[] rather than int[] arrays.
public static void dualPartition(int[] list, int[] secondary, int from, int to, int[] splitters, int splitFrom, int splitTo, int[] splitIndexes)
partition(int[],int,int,int[],int,int,int[])
except that this method synchronously
partitions two arrays at the same time; both arrays are partially sorted according to the elements of the primary
array. In other words, each time an element in the primary array is moved from index A to B, the correspoding
element within the secondary array is also moved from index A to B. Use cases:
Image having a large list of 2-dimensional points. If memory consumption and performance matter, it is a good idea to physically lay them out as two 1-dimensional arrays (using something like Point2D objects would be prohibitively expensive, both in terms of time and space). Now imagine wanting to histogram the points. We may want to partially sort the points by x-coordinate into intervals. This method efficiently does the job.
Performance:
Same as for single-partition methods.
public static int dualPartition(int[] list, int[] secondary, int from, int to, int splitter)
partition(int[],int,int,int)
except that this method synchronously partitions two arrays at
the same time; both arrays are partially sorted according to the elements of the primary array. In other words,
each time an element in the primary array is moved from index A to B, the correspoding element within the secondary
array is also moved from index A to B. Performance:
Same as for single-partition methods.
public static void genericPartition(int from, int to, int splitFrom, int splitTo, int[] splitIndexes, IntComparator comp, IntComparator comp2, IntComparator comp3, Swapper swapper)
partition(int[],int,int,int[],int,int,int[])
except that it generically partitions
arbitrary shaped data (for example matrices or multiple arrays) rather than int[] arrays. This method operates on arbitrary shaped data and arbitrary shaped splitters. In fact, it has no idea what kind of data by what kind of splitters it is partitioning. Comparisons and swapping are delegated to user provided objects which know their data and can do the job.
Lets call the generic data g (it may be a matrix, one array, three
linked lists or whatever). Lets call the generic splitters s. This class takes a user comparison function
operating on two indexes (a,b), namely an IntComparator
. The comparison function determines
whether s[a] is equal, less or greater than g[b]. This method can then decide to swap the data
g[b] with the data g[c] (yes, c, not a). It calls a user provided Swapper
object that knows how to swap the data of these two indexes.
Again, note the details: Comparisons compare s[a] with g[b]. Swaps swap g[b] with g[c]. Prior to calling this method, the generic splitters s must be sorted ascending and must not contain multiple equal values. These preconditions are not checked; be sure that they are met.
from
- the index of the first element within g to be considered.to
- the index of the last element within g to be considered. The method considers the
elements g[from] .. g[to].splitFrom
- the index of the first splitter element to be considered.splitTo
- the index of the last splitter element to be considered. The method considers the splitter
elements s[splitFrom] .. s[splitTo].splitIndexes
- a list into which this method fills the indexes of elements delimiting intervals. Upon return
splitIndexes[splitFrom..splitTo] will be set accordingly. Therefore, must satisfy
splitIndexes.length > splitTo.comp
- the comparator comparing a splitter with an element of the generic data. Takes as first
argument the index a within the generic splitters s. Takes as second argument
the index b within the generic data g.comp2
- the comparator to determine the order of the generic data. Takes as first argument the index
a within the generic data g. Takes as second argument the index b
within the generic data g.comp3
- the comparator comparing a splitter with another splitter. Takes as first argument the index
a within the generic splitters s. Takes as second argument the index
b within the generic splitters g.swapper
- an object that knows how to swap the elements at any two indexes (a,b). Takes as first argument
the index b within the generic data g. Takes as second argument the index
c within the generic data g.
Tip: Normally you will have splitIndexes.length == s.length as well as from==0, to==g.length-1 and splitFrom==0, splitTo==s.length-1.
Sorting.binarySearchFromTo(Object[], Object, int, int, Comparator)
public static void partition(double[] list, int from, int to, double[] splitters, int splitFrom, int splitTo, int[] splitIndexes)
partition(int[],int,int,int[],int,int,int[])
except that it partitions double[] rather
than int[] arrays.
public static int partition(double[] list, int from, int to, double splitter)
partition(int[],int,int,int)
except that it partitions double[] rather than
int[] arrays.
public static void partition(int[] list, int from, int to, int[] splitters, int splitFrom, int splitTo, int[] splitIndexes)
Example:
list = (7, 4, 5, 50, 6, 4, 3, 6), splitters = (5, 10, 30) defines the three intervals [-infinity,5), [5,10), [10,30). Lets define to sort the entire list (from=0, to=7) using all splitters (splitFrom==0, splitTo=2).
The method modifies the list to be list = (4, 4, 3, 6, 7, 5, 6, 50) and returns the splitIndexes = (2, 6, 6). In other words,
More formally, this method guarantees that
upon return for all j = splitFrom .. splitTo there holds:
for all i = splitIndexes[j-1]+1 ..
splitIndexes[j]: splitters[j-1] <= list[i] < splitters[j].
Performance:
Let N=to-from+1 be the number of elements to be partitioned. Let k=splitTo-splitFrom+1 be the number of splitter elements. Then we have the following time complexities
Implementation:
The algorithm can be seen as a Bentley/McIlroy quicksort where swapping and insertion sort are omitted. It is designed to detect and take advantage of skew while maintaining good performance in the uniform case.
list
- the list to be partially sorted.from
- the index of the first element within list to be considered.to
- the index of the last element within list to be considered. The method considers the
elements list[from] .. list[to].splitters
- the values at which the list shall be split into intervals. Must be sorted ascending and must
not contain multiple identical values. These preconditions are not checked; be sure that they
are met.splitFrom
- the index of the first splitter element to be considered.splitTo
- the index of the last splitter element to be considered. The method considers the splitter
elements splitters[splitFrom] .. splitters[splitTo].splitIndexes
- a list into which this method fills the indexes of elements delimiting intervals. Upon return
splitIndexes[splitFrom..splitTo] will be set accordingly. Therefore, must satisfy
splitIndexes.length > splitTo. Tip: Normally you will have splitIndexes.length == splitters.length as well as from==0, to==list.length-1 and splitFrom==0, splitTo==splitters.length-1.
Arrays
,
Arrays
public static int partition(int[] list, int from, int to, int splitter)
Example:
list = (7, 4, 5, 50, 6, 4, 3, 6), splitter = 5 defines the two intervals [-infinity,5), [5,+infinity].
The method modifies the list to be list = (4, 4, 3, 50, 6, 7, 5, 6) and returns the split index 2. In other words,
More formally, this method guarantees that upon return there holds:
Performance:
Let N=to-from+1 be the number of elements to be partially sorted. Then the time complexity is O( N ). No temporary memory is allocated; the sort is in-place.
list
- the list to be partially sorted.from
- the index of the first element within list to be considered.to
- the index of the last element within list to be considered. The method considers the
elements list[from] .. list[to].splitter
- the value at which the list shall be split.
public static void partition(java.lang.Object[] list, int from, int to, java.lang.Object[] splitters, int splitFrom, int splitTo, int[] splitIndexes, java.util.Comparator<java.lang.Object> comp)
partition(int[],int,int,int[],int,int,int[])
except that it partitions Object[] rather
than int[] arrays.
public static int partition(java.lang.Object[] list, int from, int to, java.lang.Object splitter, java.util.Comparator<java.lang.Object> comp)
partition(int[],int,int,int)
except that it synchronously partitions the objects of the
given list by the order of the given comparator.
public static void partition(DoubleArrayList list, int from, int to, DoubleArrayList splitters, IntArrayList splitIndexes)
public static void partition(IntArrayList list, int from, int to, IntArrayList splitters, IntArrayList splitIndexes)
public static void triplePartition(double[] list, double[] secondary, double[] tertiary, int from, int to, double[] splitters, int splitFrom, int splitTo, int[] splitIndexes)
triplePartition(int[],int[],int[],int,int,int[],int,int,int[])
except that it synchronously
partitions double[] rather than int[] arrays.
public static int triplePartition(double[] list, double[] secondary, double[] tertiary, int from, int to, double splitter)
triplePartition(int[],int[],int[],int,int,int)
except that it synchronously partitions
double[] rather than int[] arrays.
public static void triplePartition(int[] list, int[] secondary, int[] tertiary, int from, int to, int[] splitters, int splitFrom, int splitTo, int[] splitIndexes)
partition(int[],int,int,int[],int,int,int[])
except that this method synchronously
partitions three arrays at the same time; all three arrays are partially sorted according to the elements of the
primary array. In other words, each time an element in the primary array is moved from index A to B, the
correspoding element within the secondary array as well as the corresponding element within the tertiary array are
also moved from index A to B. Use cases:
Image having a large list of 3-dimensional points. If memory consumption and performance matter, it is a good idea to physically lay them out as three 1-dimensional arrays (using something like Point3D objects would be prohibitively expensive, both in terms of time and space). Now imagine wanting to histogram the points. We may want to partially sort the points by x-coordinate into intervals. This method efficiently does the job.
Performance:
Same as for single-partition methods.
public static int triplePartition(int[] list, int[] secondary, int[] tertiary, int from, int to, int splitter)
partition(int[],int,int,int)
except that this method synchronously partitions three arrays
at the same time; all three arrays are partially sorted according to the elements of the primary array. In other
words, each time an element in the primary array is moved from index A to B, the correspoding element within the
secondary array as well as the corresponding element within the tertiary array are also moved from index A to B.
Performance:
Same as for single-partition methods.
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