# gqlalchemy.graph_algorithms.integrated_algorithms

## IntegratedAlgorithm Objects

`class IntegratedAlgorithm(ABC)`

Abstract class modeling Memgraph's built-in graph algorithms.

These algorithms are integrated into Memgraph's codebase and are called within a relationship part of a query. For instance: MATCH p = (:City {name: "Paris"}) -[:Road * bfs (r, n | r.length <= 200 AND n.name != "Metz")]-> (:City {name: "Berlin"})

#### __str__

`@abstractmethod`

def __str__() -> str

Instance of IntegratedAlgorithm subclass is used as a string

#### to_cypher_lambda

`@staticmethod`

def to_cypher_lambda(expression: str) -> str

Method for creating a general lambda expression.

Variables `r`

and `n`

stand for relationship and node. The expression is
used e.g. for a filter lambda, to use only relationships of length less
than 200:
expression="r.length < 200"
with the filter lambda being:
(r, n | r.length < 200)

**Arguments**:

`expression`

- Lambda conditions or statements.

## BreadthFirstSearch Objects

`class BreadthFirstSearch(IntegratedAlgorithm)`

Build a BFS call for a Cypher query.

The Breadth-first search can be called in Memgraph with Cypher queries such
as: `MATCH (a {id: 723})-[*BFS ..10 (r, n | r.x > 12 AND n.y < 3)]-() RETURN *;`

It is called inside the relationship clause, `*BFS`

naming the algorithm,
`..10`

specifying depth bounds, and `(r, n | <expression>)`

is a filter
lambda.

#### __init__

`def __init__(lower_bound: int = None, upper_bound: int = None, condition: str = None) -> None`

**Arguments**:

`lower_bound`

- Lower bound for path depth. Defaults to`None`

.`upper_bound`

- Upper bound for path depth. Defaults to`None`

.`condition`

- Filter through nodes and relationships that pass this condition. Defaults to`None`

.

#### __str__

`def __str__() -> str`

Get a Cypher query string for this algorithm.

#### to_cypher_bounds

`def to_cypher_bounds() -> str`

If bounds are specified, returns them in grammar-defined form.

## DepthFirstSearch Objects

`class DepthFirstSearch(IntegratedAlgorithm)`

Build a DFS call for a Cypher query.
The Depth-First Search can be called in Memgraph with Cypher queries
such as:
MATCH (a {id: 723})-[* ..10 (r, n | r.x > 12 AND n.y < 3)]-() RETURN *;
It is called inside the relationship clause, "*" naming the algorithm
("*" without "DFS" because it is defined like such in openCypher),
"..10" specifying depth bounds, and "(r, n | <expression>)" is a filter
lambda.

#### __init__

`def __init__(lower_bound: int = None, upper_bound: int = None, condition: str = None) -> None`

**Arguments**:

`lower_bound`

- Lower bound for path depth. Defaults to None.`upper_bound`

- Upper bound for path depth. Defaults to None.`condition`

- Filter through nodes and relationships that pass this condition. Defaults to None.

#### __str__

`def __str__() -> str`

get Cypher query string for this algorithm.

#### to_cypher_bounds

`def to_cypher_bounds() -> str`

If bounds are specified, returns them in grammar-defined form.

## WeightedShortestPath Objects

`class WeightedShortestPath(IntegratedAlgorithm)`

Build a Djikstra shortest path call for a Cypher query
The weighted shortest path algorithm can be called in Memgraph with Cypher
queries such as:
" MATCH (a {id: 723})-[r *WSHORTEST 10 (r, n | r.weight) weight_sum
(r, n | r.x > 12 AND r.y < 3)]-(b {id: 882}) RETURN * "
It is called inside the relationship clause, "*WSHORTEST" naming the
algorithm, "10" specifying search depth bounds, and "(r, n | <expression>)"
is a filter lambda, used to filter which relationships and nodes to use.

#### __init__

`def __init__(upper_bound: int = None, condition: str = None, total_weight_var: str = DEFAULT_TOTAL_WEIGHT, weight_property: str = DEFAULT_WEIGHT_PROPERTY) -> None`

**Arguments**:

`upper_bound`

- Upper bound for path depth. Defaults to None.`condition`

- Filter through nodes and relationships that pass this condition. Defaults to None.`total_weight_var`

- Variable defined as the sum of all weights on path being returned. Defaults to "total_weight".`weight_property`

- property being used as weight. Defaults to "r.weight".