Partition - Maple Help
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Iterator

  

Partition

  

generate all partitions of an integer

 

Calling Sequence

Parameters

Options

Description

Examples

References

Compatibility

Calling Sequence

Partition(n, m, opts)

Parameters

n

-

posint; integer to partition

m

-

(optional) posint; maximum integer in a partition

opts

-

(optional) equation(s) of the form option = value; specify options for the Partition command

Options

• 

compile = truefalse

  

True means compile the iterator. The default is true.

Description

• 

The Partition command returns an iterator that generates all partitions of the integer n, in reverse lexicographic order.

• 

A partition of integer n is a sequence of integers a1&comma;&comma;ak such that n&equals;j&equals;1kaj and 0<ajn for j1&comma;&comma;k.

• 

The n parameter is the integer to partition.

• 

The optional m parameter is the maximum integer that can appear in any partition. The default is n.

• 

The output of the iterator is an array of fixed length n. The partition is in the indices 1 to lengthP, where P is the assigned iterator.

Methods

In addition to the common iterator methods, this iterator object has the following methods. The self parameter is the iterator object.

• 

Number(self): return the number of iterations required to step through the iterator, assuming it started at rank one.

Examples

withIterator&colon;

Iterate through the partitions of 8.

PPartition8&colon;

PrintP&comma;showrank&colon;

 1: 8
 2: 7 1
 3: 6 2
 4: 6 1 1
 5: 5 3
 6: 5 2 1
 7: 5 1 1 1
 8: 4 4
 9: 4 3 1
10: 4 2 2
11: 4 2 1 1
12: 4 1 1 1 1
13: 3 3 2
14: 3 3 1 1
15: 3 2 2 1
16: 3 2 1 1 1
17: 3 1 1 1 1 1
18: 2 2 2 2
19: 2 2 2 1 1
20: 2 2 1 1 1 1
21: 2 1 1 1 1 1 1
22: 1 1 1 1 1 1 1 1

Iterate through the partitions of 8, with maximum integer 5.

PPartition8&comma;5&colon;

PrintP&comma;showrank&colon;

 1: 5 3
 2: 5 2 1
 3: 5 1 1 1
 4: 4 4
 5: 4 3 1
 6: 4 2 2
 7: 4 2 1 1
 8: 4 1 1 1 1
 9: 3 3 2
10: 3 3 1 1
11: 3 2 2 1
12: 3 2 1 1 1
13: 3 1 1 1 1 1
14: 2 2 2 2
15: 2 2 2 1 1
16: 2 2 1 1 1 1
17: 2 1 1 1 1 1 1
18: 1 1 1 1 1 1 1 1

Compute the number of iterations.

NumberP

18

(1)

Add the elements of each partition to verify they sum to 8.

seqaddpk&comma;k=1..lengthP&comma;p=P

8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8

(2)

References

  

Knuth, Donald Ervin. The Art of Computer Programming, volume 4, fascicle 3; generating all combinations and partitions, sec. 7.2.1.4, generating all partitions, algorithm P, partitions in reverse lexicographic order.  The algorithm was corrected; Knuth_errata, p. 38.

Compatibility

• 

The Iterator[Partition] command was introduced in Maple 2016.

• 

For more information on Maple 2016 changes, see Updates in Maple 2016.

• 

The Iterator[Partition] command was updated in Maple 2022.

• 

The n and m parameters were updated in Maple 2022.

See Also

combinat[numbpart]

combinat[partition]

Iterator

Iterator[MultiPartition]

Iterator[PartitionFixedSize]

Iterator[SetPartitions]