Find pattern with Position

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3
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I have a list a = L, S, L, L, S and I can find the position of of either L or S by:

Position[a, L, S]

But what if I want to find IF the a segment L,S exists?

Ideally, I would like to know how many such patterns exist and how many elements separate them.

list-manipulation pattern-matching

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asked 1 hour ago

SuperCiocia

347210

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up vote
3
down vote

favorite

I have a list a = L, S, L, L, S and I can find the position of of either L or S by:

Position[a, L, S]

But what if I want to find IF the a segment L,S exists?

Ideally, I would like to know how many such patterns exist and how many elements separate them.

list-manipulation pattern-matching

share|improve this question

asked 1 hour ago

SuperCiocia

347210

add a comment | 

up vote
3
down vote

favorite

up vote
3
down vote

favorite

I have a list a = L, S, L, L, S and I can find the position of of either L or S by:

Position[a, L, S]

But what if I want to find IF the a segment L,S exists?

Ideally, I would like to know how many such patterns exist and how many elements separate them.

list-manipulation pattern-matching

share|improve this question

asked 1 hour ago

SuperCiocia

347210

I have a list a = L, S, L, L, S and I can find the position of of either L or S by:

Position[a, L, S]

But what if I want to find IF the a segment L,S exists?

Ideally, I would like to know how many such patterns exist and how many elements separate them.

list-manipulation pattern-matching

list-manipulation pattern-matching

share|improve this question

asked 1 hour ago

SuperCiocia

347210

share|improve this question

asked 1 hour ago

SuperCiocia

347210

share|improve this question

share|improve this question

asked 1 hour ago

SuperCiocia

347210

asked 1 hour ago

SuperCiocia

347210

asked 1 hour ago

SuperCiocia

347210

347210

add a comment | 

add a comment | 

2 Answers
2

active

oldest

votes

up vote
2
down vote

One way to approach this would be to partition the sequence into pairs and then find the positions of the pairs:

ls = Position[Partition[a, 2, 1], L, S]

which shows that the two L, Ss occur at the first and fourth positions. To find the separation between the occurrences:

Differences[ls]

To get the number of occurrences:

Length[ls] 

If there are no occurrences, then you will get 0.

share|improve this answer

edited 57 mins ago

answered 1 hour ago

bill s

50.8k373144

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up vote
2
down vote

SequenceCases[a, L, S]

L, S, L, S

SequencePosition[a, L, S]

1, 2, 4, 5

SequenceCount[a, L, S]

2

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answered 49 mins ago

Henrik Schumacher

37.8k249108

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2 Answers
2

active

oldest

votes

2 Answers
2

active

oldest

votes

active

oldest

votes

active

oldest

votes

up vote
2
down vote

One way to approach this would be to partition the sequence into pairs and then find the positions of the pairs:

ls = Position[Partition[a, 2, 1], L, S]

which shows that the two L, Ss occur at the first and fourth positions. To find the separation between the occurrences:

Differences[ls]

To get the number of occurrences:

Length[ls] 

If there are no occurrences, then you will get 0.

share|improve this answer

edited 57 mins ago

answered 1 hour ago

bill s

50.8k373144

add a comment | 

up vote
2
down vote

One way to approach this would be to partition the sequence into pairs and then find the positions of the pairs:

ls = Position[Partition[a, 2, 1], L, S]

which shows that the two L, Ss occur at the first and fourth positions. To find the separation between the occurrences:

Differences[ls]

To get the number of occurrences:

Length[ls] 

If there are no occurrences, then you will get 0.

share|improve this answer

edited 57 mins ago

answered 1 hour ago

bill s

50.8k373144

add a comment | 

up vote
2
down vote

up vote
2
down vote

One way to approach this would be to partition the sequence into pairs and then find the positions of the pairs:

ls = Position[Partition[a, 2, 1], L, S]

which shows that the two L, Ss occur at the first and fourth positions. To find the separation between the occurrences:

Differences[ls]

To get the number of occurrences:

Length[ls] 

If there are no occurrences, then you will get 0.

share|improve this answer

edited 57 mins ago

answered 1 hour ago

bill s

50.8k373144

One way to approach this would be to partition the sequence into pairs and then find the positions of the pairs:

ls = Position[Partition[a, 2, 1], L, S]

which shows that the two L, Ss occur at the first and fourth positions. To find the separation between the occurrences:

Differences[ls]

To get the number of occurrences:

Length[ls] 

If there are no occurrences, then you will get 0.

share|improve this answer

edited 57 mins ago

answered 1 hour ago

bill s

50.8k373144

share|improve this answer

share|improve this answer

edited 57 mins ago

edited 57 mins ago

edited 57 mins ago

answered 1 hour ago

bill s

50.8k373144

answered 1 hour ago

bill s

50.8k373144

answered 1 hour ago

bill s

50.8k373144

50.8k373144

add a comment | 

add a comment | 

up vote
2
down vote

SequenceCases[a, L, S]

L, S, L, S

SequencePosition[a, L, S]

1, 2, 4, 5

SequenceCount[a, L, S]

2

share|improve this answer

answered 49 mins ago

Henrik Schumacher

37.8k249108

add a comment | 

up vote
2
down vote

SequenceCases[a, L, S]

L, S, L, S

SequencePosition[a, L, S]

1, 2, 4, 5

SequenceCount[a, L, S]

2

share|improve this answer

answered 49 mins ago

Henrik Schumacher

37.8k249108

add a comment | 

up vote
2
down vote

up vote
2
down vote

SequenceCases[a, L, S]

L, S, L, S

SequencePosition[a, L, S]

1, 2, 4, 5

SequenceCount[a, L, S]

2

share|improve this answer

answered 49 mins ago

Henrik Schumacher

37.8k249108

SequenceCases[a, L, S]

L, S, L, S

SequencePosition[a, L, S]

1, 2, 4, 5

SequenceCount[a, L, S]

2

share|improve this answer

answered 49 mins ago

Henrik Schumacher

37.8k249108

share|improve this answer

share|improve this answer

answered 49 mins ago

Henrik Schumacher

37.8k249108

answered 49 mins ago

Henrik Schumacher

37.8k249108

answered 49 mins ago

Henrik Schumacher

37.8k249108

37.8k249108

add a comment | 

add a comment | 

 

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