---
title: Publisher Operators
framework: combine
role: collectionGroup
role_heading: API Collection
path: combine/publishers-sequence-publisher-operators
---

# Publisher Operators

Methods that create downstream publishers or subscribers to act on the elements they receive.

## Topics

### Mapping elements

- [map(_:)](combine/publishers/sequence/map(_:).md)
- [scan(_:_:)](combine/publishers/sequence/scan(_:_:).md)
- [setFailureType(to:)](combine/publishers/sequence/setfailuretype(to:).md)
- [replaceNil(with:)](combine/publishers/sequence/replacenil(with:).md)

### Filtering elements

- [filter(_:)](combine/publishers/sequence/filter(_:).md)
- [compactMap(_:)](combine/publishers/sequence/compactmap(_:).md)
- [removeDuplicates()](combine/publishers/sequence/removeduplicates().md)

### Reducing elements

- [collect()](combine/publishers/sequence/collect().md)
- [ignoreOutput()](combine/publishers/sequence/ignoreoutput().md)
- [reduce(_:_:)](combine/publishers/sequence/reduce(_:_:).md)
- [tryReduce(_:_:)](combine/publishers/sequence/tryreduce(_:_:).md)

### Applying mathematical operations on elements

- [count()](combine/publishers/sequence/count()-5rrw2.md)
- [count()](combine/publishers/sequence/count()-5hb52.md)
- [count()](combine/publishers/sequence/count()-b8ct.md)
- [max()](combine/publishers/sequence/max().md)
- [max(by:)](combine/publishers/sequence/max(by:).md)
- [min()](combine/publishers/sequence/min().md)
- [min(by:)](combine/publishers/sequence/min(by:).md)

### Applying matching criteria to elements

- [contains(_:)](combine/publishers/sequence/contains(_:).md)
- [contains(where:)](combine/publishers/sequence/contains(where:).md)
- [tryContains(where:)](combine/publishers/sequence/trycontains(where:).md)
- [allSatisfy(_:)](combine/publishers/sequence/allsatisfy(_:).md)
- [tryAllSatisfy(_:)](combine/publishers/sequence/tryallsatisfy(_:).md)

### Applying sequence operations to elements

- [dropFirst(_:)](combine/publishers/sequence/dropfirst(_:).md)
- [drop(while:)](combine/publishers/sequence/drop(while:).md)
- [append(_:)](combine/publishers/sequence/append(_:)-45rm8.md)
- [append(_:)](combine/publishers/sequence/append(_:)-3dj6k.md)
- [append(_:)](combine/publishers/sequence/append(_:)-2knh4.md)
- [prepend(_:)](combine/publishers/sequence/prepend(_:)-1r564.md)
- [prepend(_:)](combine/publishers/sequence/prepend(_:)-71f7p.md)
- [prepend(_:)](combine/publishers/sequence/prepend(_:)-2ros1.md)
- [prefix(_:)](combine/publishers/sequence/prefix(_:).md)
- [prefix(while:)](combine/publishers/sequence/prefix(while:).md)

### Selecting specific elements

- [first()](combine/publishers/sequence/first().md)
- [first(where:)](combine/publishers/sequence/first(where:).md)
- [last()](combine/publishers/sequence/last().md)
- [last(where:)](combine/publishers/sequence/last(where:).md)
- [output(at:)](combine/publishers/sequence/output(at:)-3r7zo.md)
- [output(at:)](combine/publishers/sequence/output(at:)-9kto7.md)
- [output(in:)](combine/publishers/sequence/output(in:)-6g2zc.md)
- [output(in:)](combine/publishers/sequence/output(in:)-8l6yw.md)