#
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# this work for additional information regarding copyright ownership.
# The ASF licenses this file to You under the Apache License, Version 2.0
# (the "License"); you may not use this file except in compliance with
# the License. You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
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from __future__ import annotations
import warnings
from typing import TYPE_CHECKING, Any, List, Optional
from pyspark.sql import functions as F
from pyspark.storagelevel import StorageLevel
from pyspark.version import __version__
from typing_extensions import override
if __version__[:3] >= "3.4":
from pyspark.sql.utils import is_remote
else:
# All the Connect-related utilities are accessible starting from 3.4.x
def is_remote() -> bool:
return False
from graphframes.classic.graphframe import GraphFrame as GraphFrameClassic
from graphframes.lib import Pregel
if TYPE_CHECKING:
from pyspark.sql import Column, DataFrame
from graphframes.connect.graphframes_client import GraphFrameConnect
"""Constant for the vertices ID column name."""
ID = "id"
"""Constant for the edge src column name."""
SRC = "src"
"""Constant for the edge dst column name."""
DST = "dst"
"""Constant for the edge column name."""
EDGE = "edge"
[docs]
class GraphFrame:
"""
Represents a graph with vertices and edges stored as DataFrames.
:param v: :class:`DataFrame` holding vertex information.
Must contain a column named "id" that stores unique
vertex IDs.
:param e: :class:`DataFrame` holding edge information.
Must contain two columns "src" and "dst" storing source
vertex IDs and destination vertex IDs of edges, respectively.
>>> localVertices = [(1,"A"), (2,"B"), (3, "C")]
>>> localEdges = [(1,2,"love"), (2,1,"hate"), (2,3,"follow")]
>>> v = spark.createDataFrame(localVertices, ["id", "name"])
>>> e = spark.createDataFrame(localEdges, ["src", "dst", "action"])
>>> g = GraphFrame(v, e)
"""
ID: str = ID
SRC: str = SRC
DST: str = DST
EDGE: str = EDGE
@staticmethod
def _from_impl(impl: "GraphFrameClassic | GraphFrameConnect") -> "GraphFrame":
return GraphFrame(impl._vertices, impl._edges)
def __init__(self, v: DataFrame, e: DataFrame) -> None:
"""
Initialize a GraphFrame from vertex DataFrame and edges DataFrame.
:param v: :class:`DataFrame` holding vertex information.
Must contain a column named "id" that stores unique
vertex IDs.
:param e: :class:`DataFrame` holding edge information.
Must contain two columns "src" and "dst" storing source
vertex IDs and destination vertex IDs of edges, respectively.
"""
self._impl: "GraphFrameClassic | GraphFrameConnect"
if self.ID not in v.columns:
raise ValueError(
"Vertex ID column {} missing from vertex DataFrame, which has columns: {}".format(
self.ID, ",".join(v.columns)
)
)
if self.SRC not in e.columns:
raise ValueError(
"Source vertex ID column {} missing from edge DataFrame, which has columns: {}".format( # noqa: E501
self.SRC, ",".join(e.columns)
)
)
if self.DST not in e.columns:
raise ValueError(
"Destination vertex ID column {} missing from edge DataFrame, which has columns: {}".format( # noqa: E501
self.DST, ",".join(e.columns)
)
)
if is_remote():
from graphframes.connect.graphframes_client import GraphFrameConnect
self._impl = GraphFrameConnect(v, e) # ty: ignore[invalid-argument-type]
else:
self._impl = GraphFrameClassic(v, e) # ty: ignore[invalid-argument-type]
@property
def vertices(self) -> DataFrame:
"""
:class:`DataFrame` holding vertex information, with unique column "id"
for vertex IDs.
"""
return self._impl._vertices
@property
def edges(self) -> DataFrame:
"""
:class:`DataFrame` holding edge information, with unique columns "src" and
"dst" storing source vertex IDs and destination vertex IDs of edges,
respectively.
"""
return self._impl._edges
@property
def nodes(self) -> DataFrame:
"""Alias to vertices."""
return self.vertices
@override
def __repr__(self) -> str:
# Exactly like in the scala core
v_cols = [self.ID] + [col for col in self._impl._vertices.columns if col != self.ID]
e_cols = [self.SRC, self.DST] + [
col for col in self._impl._edges.columns if col not in {self.SRC, self.DST}
]
v = self._impl._vertices.select(*v_cols).__repr__()
e = self._impl._edges.select(*e_cols).__repr__()
return f"GraphFrame(v:{v}, e:{e})"
[docs]
def cache(self) -> "GraphFrame":
"""Persist the dataframe representation of vertices and edges of the graph with the default
storage level.
"""
new_vertices = self._impl._vertices.cache()
new_edges = self._impl._edges.cache()
return GraphFrame(new_vertices, new_edges)
[docs]
def persist(self, storageLevel: StorageLevel = StorageLevel.MEMORY_ONLY) -> "GraphFrame":
"""Persist the dataframe representation of vertices and edges of the graph with the given
storage level.
"""
new_vertices = self._impl._vertices.persist(storageLevel=storageLevel)
new_edges = self._impl._edges.persist(storageLevel=storageLevel)
return GraphFrame(new_vertices, new_edges)
[docs]
def unpersist(self, blocking: bool = False) -> "GraphFrame":
"""Mark the dataframe representation of vertices and edges of the graph as non-persistent,
and remove all blocks for it from memory and disk.
"""
new_vertices = self._impl._vertices.unpersist(blocking=blocking)
new_edges = self._impl._edges.unpersist(blocking=blocking)
return GraphFrame(new_vertices, new_edges)
@property
def outDegrees(self) -> DataFrame:
"""
The out-degree of each vertex in the graph, returned as a DataFrame with two columns:
- "id": the ID of the vertex
- "outDegree" (integer) storing the out-degree of the vertex
Note that vertices with 0 out-edges are not returned in the result.
:return: DataFrame with new vertices column "outDegree"
"""
return self._impl._edges.groupBy(F.col(self.SRC).alias(self.ID)).agg(
F.count("*").alias("outDegree")
)
@property
def inDegrees(self) -> DataFrame:
"""
The in-degree of each vertex in the graph, returned as a DataFame with two columns:
- "id": the ID of the vertex
- "inDegree" (int) storing the in-degree of the vertex
Note that vertices with 0 in-edges are not returned in the result.
:return: DataFrame with new vertices column "inDegree"
"""
return self._impl._edges.groupBy(F.col(self.DST).alias(self.ID)).agg(
F.count("*").alias("inDegree")
)
@property
def degrees(self) -> DataFrame:
"""
The degree of each vertex in the graph, returned as a DataFrame with two columns:
- "id": the ID of the vertex
- 'degree' (integer) the degree of the vertex
Note that vertices with 0 edges are not returned in the result.
:return: DataFrame with new vertices column "degree"
"""
return (
self._impl._edges.select(
F.explode(F.array(F.col(self.SRC), F.col(self.DST))).alias(self.ID)
)
.groupBy(self.ID)
.agg(F.count("*").alias("degree"))
)
[docs]
def type_out_degree(
self, edge_type_col: str, edge_types: Optional[List[Any]] = None
) -> DataFrame:
"""
The out-degree of each vertex per edge type, returned as a DataFrame with two columns:
- "id": the ID of the vertex
- "outDegrees": a struct with a field for each edge type, storing the out-degree count
:param edge_type_col: Name of the column in edges DataFrame that contains edge types
:param edge_types: Optional list of edge type values. If None, edge types will be
discovered automatically.
:return: DataFrame with columns "id" and "outDegrees" (struct type)
"""
if edge_types is not None:
pivot_df = self._impl._edges.groupBy(F.col(self.SRC).alias(self.ID)).pivot(
edge_type_col, edge_types
)
else:
pivot_df = self._impl._edges.groupBy(F.col(self.SRC).alias(self.ID)).pivot(
edge_type_col
)
count_df = pivot_df.agg(F.count(F.lit(1))).na.fill(0)
struct_cols = [
F.col(col_name).cast("int").alias(col_name)
for col_name in count_df.columns
if col_name != self.ID
]
return count_df.select(F.col(self.ID), F.struct(*struct_cols).alias("outDegrees"))
[docs]
def type_in_degree(
self, edge_type_col: str, edge_types: Optional[List[Any]] = None
) -> DataFrame:
"""
The in-degree of each vertex per edge type, returned as a DataFrame with two columns:
- "id": the ID of the vertex
- "inDegrees": a struct with a field for each edge type, storing the in-degree count
:param edge_type_col: Name of the column in edges DataFrame that contains edge types
:param edge_types: Optional list of edge type values. If None, edge types will be
discovered automatically.
:return: DataFrame with columns "id" and "inDegrees" (struct type)
"""
if edge_types is not None:
pivot_df = self._impl._edges.groupBy(F.col(self.DST).alias(self.ID)).pivot(
edge_type_col, edge_types
)
else:
pivot_df = self._impl._edges.groupBy(F.col(self.DST).alias(self.ID)).pivot(
edge_type_col
)
count_df = pivot_df.agg(F.count(F.lit(1))).na.fill(0)
struct_cols = [
F.col(col_name).cast("int").alias(col_name)
for col_name in count_df.columns
if col_name != self.ID
]
return count_df.select(F.col(self.ID), F.struct(*struct_cols).alias("inDegrees"))
[docs]
def type_degree(self, edge_type_col: str, edge_types: Optional[List[Any]] = None) -> DataFrame:
"""
The total degree of each vertex per edge type (both in and out), returned as a DataFrame
with two columns:
- "id": the ID of the vertex
- "degrees": a struct with a field for each edge type, storing the total degree count
:param edge_type_col: Name of the column in edges DataFrame that contains edge types
:param edge_types: Optional list of edge type values. If None, edge types will be
discovered automatically.
:return: DataFrame with columns "id" and "degrees" (struct type)
"""
exploded_edges = self._impl._edges.select(
F.explode(F.array(F.col(self.SRC), F.col(self.DST))).alias(self.ID),
F.col(edge_type_col),
)
if edge_types is not None:
pivot_df = exploded_edges.groupBy(self.ID).pivot(edge_type_col, edge_types)
else:
pivot_df = exploded_edges.groupBy(self.ID).pivot(edge_type_col)
count_df = pivot_df.agg(F.count(F.lit(1))).na.fill(0)
struct_cols = [
F.col(col_name).cast("int").alias(col_name)
for col_name in count_df.columns
if col_name != self.ID
]
return count_df.select(F.col(self.ID), F.struct(*struct_cols).alias("degrees"))
@property
def triplets(self) -> DataFrame:
"""
The triplets (source vertex)-[edge]->(destination vertex) for all edges in the graph.
Returned as a :class:`DataFrame` with three columns:
- "src": source vertex with schema matching 'vertices'
- "edge": edge with schema matching 'edges'
- 'dst': destination vertex with schema matching 'vertices'
:return: DataFrame with columns 'src', 'edge', and 'dst'
"""
return self._impl.triplets
@property
def pregel(self) -> Pregel:
"""
Get the :class:`graphframes.classic.pregel.Pregel`
or :class`graphframes.connect.graphframes_client.Pregel`
object for running pregel.
See :class:`graphframes.lib.Pregel` for more details.
"""
return self._impl.pregel
[docs]
def find(self, pattern: str) -> DataFrame:
"""
Motif finding.
See Scala documentation for more details.
:param pattern: String describing the motif to search for.
:return: DataFrame with one Row for each instance of the motif found
"""
return self._impl.find(pattern=pattern)
[docs]
def filterVertices(self, condition: str | Column) -> "GraphFrame":
"""
Filters the vertices based on expression, remove edges containing any dropped vertices.
:param condition: String or Column describing the condition expression for filtering.
:return: GraphFrame with filtered vertices and edges.
"""
return GraphFrame._from_impl(self._impl.filterVertices(condition=condition))
[docs]
def filterEdges(self, condition: str | Column) -> "GraphFrame":
"""
Filters the edges based on expression, keep all vertices.
:param condition: String or Column describing the condition expression for filtering.
:return: GraphFrame with filtered edges.
"""
return GraphFrame._from_impl(self._impl.filterEdges(condition=condition))
[docs]
def dropIsolatedVertices(self) -> "GraphFrame":
"""
Drops isolated vertices, vertices are not contained in any edges.
:return: GraphFrame with filtered vertices.
"""
return GraphFrame._from_impl(self._impl.dropIsolatedVertices())
[docs]
def detectingCycles(
self,
checkpoint_interval: int = 2,
use_local_checkpoints: bool = False,
storage_level: StorageLevel = StorageLevel.MEMORY_AND_DISK_DESER,
) -> DataFrame:
"""Find all cycles in the graph.
An implementation of the Rocha–Thatte cycle detection algorithm.
Rocha, Rodrigo Caetano, and Bhalchandra D. Thatte. "Distributed cycle detection in
large-scale sparse graphs." Proceedings of Simpósio Brasileiro de Pesquisa Operacional
(SBPO’15) (2015): 1-11.
Returns a DataFrame with unique cycles.
:param checkpoint_interval: Pregel checkpoint interval, default is 2
:param use_local_checkpoints: should local checkpoints be used instead of checkpointDir
:storage_level: the level of storage for both intermediate results and an output DataFrame
:return: Persisted DataFrame with all the cycles
"""
return self._impl.detectingCycles(checkpoint_interval, use_local_checkpoints, storage_level)
[docs]
def bfs(
self,
fromExpr: str,
toExpr: str,
edgeFilter: str | None = None,
maxPathLength: int = 10,
) -> DataFrame:
"""
Breadth-first search (BFS).
See Scala documentation for more details.
:return: DataFrame with one Row for each shortest path between matching vertices.
"""
return self._impl.bfs(
fromExpr=fromExpr,
toExpr=toExpr,
edgeFilter=edgeFilter,
maxPathLength=maxPathLength,
)
[docs]
def aggregateMessages(
self,
aggCol: list[Column | str] | Column,
sendToSrc: list[Column | str] | Column | str | None = None,
sendToDst: list[Column | str] | Column | str | None = None,
intermediate_storage_level: StorageLevel = StorageLevel.MEMORY_AND_DISK_DESER,
) -> DataFrame:
"""
Aggregates messages from the neighbours.
When specifying the messages and aggregation function, the user may reference columns using
the static methods in :class:`graphframes.lib.AggregateMessages`.
See Scala documentation for more details.
Warning! The result of this method is persisted DataFrame object! Users should handle unpersist
to avoid possible memory leaks!
:param aggCol: the requested aggregation output either as a collection of
:class:`pyspark.sql.Column` or SQL expression string
:param sendToSrc: message sent to the source vertex of each triplet either as
a collection of :class:`pyspark.sql.Column` or SQL expression string (default: None)
:param sendToDst: message sent to the destination vertex of each triplet either as
collection of :class:`pyspark.sql.Column` or SQL expression string (default: None)
:param intermediate_storage_level: the level of intermediate storage that will be used
for both intermediate result and the output.
:return: Persisted DataFrame with columns for the vertex ID and the resulting aggregated message.
The name of the resulted message column is based on the alias of the provided aggCol!
""" # noqa: E501
if sendToDst is None:
sendToDst = []
if sendToSrc is None:
sendToSrc = []
# Back-compatibility workaround
if not isinstance(aggCol, list):
warnings.warn(
"Passing single column to aggCol is deprecated, use list",
DeprecationWarning,
)
return self.aggregateMessages(
[aggCol], sendToSrc, sendToDst, intermediate_storage_level
)
if not isinstance(sendToSrc, list):
warnings.warn(
"Passing single column to sendToSrc is deprecated, use list",
DeprecationWarning,
)
return self.aggregateMessages(
aggCol, [sendToSrc], sendToDst, intermediate_storage_level
)
if not isinstance(sendToDst, list):
warnings.warn(
"Passing single column to sendToDst is deprecated, use list",
DeprecationWarning,
)
return self.aggregateMessages(
aggCol, sendToSrc, [sendToDst], intermediate_storage_level
)
if len(aggCol) == 0:
raise TypeError("At least one aggregation column should be provided!")
if (len(sendToSrc) == 0) and (len(sendToDst) == 0):
raise ValueError("Either `sendToSrc`, `sendToDst`, or both have to be provided")
return self._impl.aggregateMessages(
aggCol=aggCol,
sendToSrc=sendToSrc,
sendToDst=sendToDst,
intermediate_storage_level=intermediate_storage_level,
)
# Standard algorithms
[docs]
def connectedComponents(
self,
algorithm: str = "graphframes",
checkpointInterval: int = 2,
broadcastThreshold: int = 1000000,
useLabelsAsComponents: bool = False,
use_local_checkpoints: bool = False,
max_iter: int = 2 ^ 31 - 2,
storage_level: StorageLevel = StorageLevel.MEMORY_AND_DISK_DESER,
) -> DataFrame:
"""
Computes the connected components of the graph.
See Scala documentation for more details.
:param algorithm: connected components algorithm to use (default: "graphframes")
Supported algorithms are "graphframes" and "graphx".
:param checkpointInterval: checkpoint interval in terms of number of iterations (default: 2)
:param broadcastThreshold: broadcast threshold in propagating component assignments
(default: 1000000). Passing -1 disable manual broadcasting and
allows AQE to handle skewed joins. This mode is much faster
and is recommended to use. Default value may be changed to -1
in the future versions of GraphFrames.
:param useLabelsAsComponents: if True, uses the vertex labels as components, otherwise will
use longs
:param use_local_checkpoints: should local checkpoints be used, default false;
local checkpoints are faster and does not require to set
a persistent checkpointDir; from the other side, local
checkpoints are less reliable and require executors to have
big enough local disks.
:param storage_level: storage level for both intermediate and final dataframes.
:return: DataFrame with new vertices column "component"
"""
return self._impl.connectedComponents(
algorithm=algorithm,
checkpointInterval=checkpointInterval,
broadcastThreshold=broadcastThreshold,
useLabelsAsComponents=useLabelsAsComponents,
use_local_checkpoints=use_local_checkpoints,
max_iter=max_iter,
storage_level=storage_level,
)
[docs]
def maximal_independent_set(
self,
seed: int = 42,
checkpoint_interval: int = 2,
use_local_checkpoints: bool = False,
storage_level: StorageLevel = StorageLevel.MEMORY_AND_DISK_DESER,
) -> DataFrame:
"""
This method implements a distributed algorithm for finding a Maximal Independent Set (MIS)
in a graph.
An MIS is a set of vertices such that no two vertices in the set are adjacent (i.e., there
is no edge between any two vertices in the set), and the set is maximal, meaning that adding
any other vertex to the set would violate the independence property. Note that this
implementation finds a maximal (but not necessarily maximum) independent set; that is, it
ensures no more vertices can be added to the set, but does not guarantee that the set has
the largest possible number of vertices among all possible independent sets in the graph.
The algorithm implemented here is based on the paper: Ghaffari, Mohsen. "An improved
distributed algorithm for maximal independent set." Proceedings of the twenty-seventh annual
ACM-SIAM symposium on Discrete algorithms. Society for Industrial and Applied Mathematics,
2016.
Note: This is a randomized, non-deterministic algorithm. The result may vary between runs
even if a fixed random seed is provided because of how Apache Spark works.
:param seed: random seed used for tie-breaking in the algorithm (default: 42)
:param checkpoint_interval: checkpoint interval in terms of number of iterations (default: 2)
:param use_local_checkpoints: whether to use local checkpoints (default: False);
local checkpoints are faster and do not require setting
a persistent checkpoint directory; however, they are less
reliable and require executors to have sufficient local disk space.
:param storage_level: storage level for both intermediate and final DataFrames
(default: MEMORY_AND_DISK_DESER)
:return: DataFrame with new vertex column "selected", where "true" indicates the vertex
is part of the Maximal Independent Set
""" # noqa: E501
return self._impl.maximal_independent_set(
checkpoint_interval, storage_level, use_local_checkpoints, seed
)
[docs]
def k_core(
self,
checkpoint_interval: int = 2,
use_local_checkpoints: bool = False,
storage_level: StorageLevel = StorageLevel.MEMORY_AND_DISK_DESER,
) -> DataFrame:
"""
The k-core is the maximal subgraph such that every vertex has at least degree k.
The k-core metric is a measure of the centrality of a node in a network, based on its
degree and the degrees of its neighbors. Nodes with higher k-core values are considered
to be more central and influential within the network.
This implementation is based on the algorithm described in:
Mandal, Aritra, and Mohammad Al Hasan. "A distributed k-core decomposition algorithm
on spark." 2017 IEEE International Conference on Big Data (Big Data). IEEE, 2017.
:param checkpoint_interval: Pregel checkpoint interval, default is 2
:param use_local_checkpoints: should local checkpoints be used instead of checkpointDir
:param storage_level: the level of storage for both intermediate results and an output DataFrame
:return: Persisted DataFrame with ID and k-core values (column "kcore")
""" # noqa: E501
return self._impl.k_core(checkpoint_interval, use_local_checkpoints, storage_level)
[docs]
def labelPropagation(
self,
maxIter: int,
algorithm: str = "graphx",
use_local_checkpoints: bool = False,
checkpoint_interval: int = 2,
storage_level: StorageLevel = StorageLevel.MEMORY_AND_DISK_DESER,
) -> DataFrame:
"""
Runs static label propagation for detecting communities in networks.
See Scala documentation for more details.
:param maxIter: the number of iterations to be performed
:param algorithm: implementation to use, posible values are "graphframes" and "graphx";
"graphx" is faster for small-medium sized graphs,
"graphframes" requires less amount of memory
:param use_local_checkpoints: should local checkpoints be used, default false;
local checkpoints are faster and does not require to set
a persistent checkpointDir; from the other side, local
checkpoints are less reliable and require executors to have
big enough local disks.
:checkpoint_interval: How often should the intermediate result be checkpointed;
Using big value here may tend to huge logical plan growth due
to the iterative nature of the algorithm.
:param storage_level: storage level for both intermediate and final dataframes.
:return: Persisted DataFrame with new vertices column "label"
"""
return self._impl.labelPropagation(
maxIter=maxIter,
algorithm=algorithm,
use_local_checkpoints=use_local_checkpoints,
checkpoint_interval=checkpoint_interval,
storage_level=storage_level,
)
[docs]
def shortestPaths(
self,
landmarks: list[str | int],
algorithm: str = "graphx",
use_local_checkpoints: bool = False,
checkpoint_interval: int = 2,
storage_level: StorageLevel = StorageLevel.MEMORY_AND_DISK_DESER,
is_directed: bool = True,
) -> DataFrame:
"""
Runs the shortest path algorithm from a set of landmark vertices in the graph.
See Scala documentation for more details.
:param landmarks: a set of one or more landmarks
:param algorithm: implementation to use, posible values are "graphframes" and "graphx";
"graphx" is faster for small-medium sized graphs,
"graphframes" requires less amount of memory
:param use_local_checkpoints: should local checkpoints be used, default false;
local checkpoints are faster and does not require to set
a persistent checkpointDir; from the other side, local
checkpoints are less reliable and require executors to have
big enough local disks.
:param checkpoint_interval: How often should the intermediate result be checkpointed;
Using big value here may tend to huge logical plan growth due
to the iterative nature of the algorithm.
:param storage_level: storage level for both intermediate and final dataframes.
:param is_directed: should algorithm find directed paths or any paths.
:return: persistent DataFrame with new vertices column "distances"
""" # noqa: E501
return self._impl.shortestPaths(
landmarks=landmarks,
algorithm=algorithm,
use_local_checkpoints=use_local_checkpoints,
checkpoint_interval=checkpoint_interval,
storage_level=storage_level,
is_directed=is_directed,
)
[docs]
def stronglyConnectedComponents(self, maxIter: int) -> DataFrame:
"""
Runs the strongly connected components algorithm on this graph.
See Scala documentation for more details.
:param maxIter: the number of iterations to run
:return: DataFrame with new vertex column "component"
"""
return self._impl.stronglyConnectedComponents(maxIter=maxIter)
[docs]
def svdPlusPlus(
self,
rank: int = 10,
maxIter: int = 2,
minValue: float = 0.0,
maxValue: float = 5.0,
gamma1: float = 0.007,
gamma2: float = 0.007,
gamma6: float = 0.005,
gamma7: float = 0.015,
) -> tuple[DataFrame, float]:
"""
Runs the SVD++ algorithm.
See Scala documentation for more details.
:return: Tuple of DataFrame with new vertex columns storing learned model, and loss value
"""
return self._impl.svdPlusPlus(
rank=rank,
maxIter=maxIter,
minValue=minValue,
maxValue=maxValue,
gamma1=gamma1,
gamma2=gamma2,
gamma6=gamma6,
gamma7=gamma7,
)
[docs]
def triangleCount(self, storage_level: StorageLevel) -> DataFrame:
"""
Counts the number of triangles passing through each vertex in this graph.
This impementation is based on the computing the intersection of
vertices neighborhoods. It requires to collect the whole neighborhood of
each vertex. It may fail because of memory errors on graphs with power law
degrees distribution (graphs with a few very high-degree vertices). Consider
edges sampling for that case to get an approximate count of trangles.
:param storage_level: storage level that is used for both
intermediate and final dataframes.
:return: DataFrame with new vertex column "count"
"""
return self._impl.triangleCount(storage_level=storage_level)
[docs]
def powerIterationClustering(
self, k: int, maxIter: int, weightCol: str | None = None
) -> DataFrame:
"""
Power Iteration Clustering (PIC), a scalable graph clustering algorithm developed by Lin and Cohen.
From the abstract: PIC finds a very low-dimensional embedding of a dataset using truncated power iteration
on a normalized pair-wise similarity matrix of the data.
:param k: the numbers of clusters to create
:param maxIter: param for maximum number of iterations (>= 0)
:param weightCol: optional name of weight column, 1.0 is used if not provided
:return: DataFrame with new column "cluster"
""" # noqa: E501
return self._impl.powerIterationClustering(k, maxIter, weightCol)
[docs]
def validate(
self,
check_vertices: bool = True,
intermediate_storage_level: StorageLevel = StorageLevel.MEMORY_AND_DISK_DESER,
) -> None:
"""
Validates the consistency and integrity of a graph by performing checks on the vertices and
edges.
:param check_vertices: a flag to indicate whether additional vertex consistency checks
should be performed. If true, the method will verify that all vertices in the vertex
DataFrame are represented in the edge DataFrame and vice versa. It is slow on big graphs.
:param intermediate_storage_level: the storage level to be used when persisting
intermediate DataFrame computations during the validation process.
:return: Unit, as the method performs validation checks and throws an exception if
validation fails.
:raises ValueError: if there are any inconsistencies in the graph, such as duplicate
vertices, mismatched vertices between edges and vertex DataFrames or missing
connections.
""" # noqa: E501
persisted_vertices = self.vertices.persist(intermediate_storage_level)
row = persisted_vertices.select(F.count_distinct(F.col(ID))).first()
assert row is not None # for type checker
count_distinct_vertices = row[0]
assert isinstance(count_distinct_vertices, int) # for type checker
total_count_vertices = persisted_vertices.count()
if count_distinct_vertices != total_count_vertices:
_msg = "Graph contains ({}) duplicate vertices."
raise ValueError(_msg.format(total_count_vertices - count_distinct_vertices))
if check_vertices:
vertices_set_from_edges = (
self.edges.select(F.col(SRC).alias(ID))
.union(self.edges.select(F.col(DST).alias(ID)))
.distinct()
.persist(intermediate_storage_level)
)
count_vertices_from_edges = vertices_set_from_edges.count()
if count_vertices_from_edges > count_distinct_vertices:
_msg = "Graph is inconsistent: edges has {} "
_msg += "vertices, but vertices has {} vertices."
raise ValueError(_msg.format(count_vertices_from_edges, count_distinct_vertices))
combined = vertices_set_from_edges.join(self.vertices, ID, "left_anti")
count_of_bad_vertices = combined.count()
if count_of_bad_vertices > 0:
_msg = "Vertices DataFrame does not contain all edges src/dst. "
_msg += "Found {} edges src/dst that are not in the vertices DataFrame."
raise ValueError(_msg.format(count_of_bad_vertices))
_ = vertices_set_from_edges.unpersist()
_ = persisted_vertices.unpersist()
[docs]
def as_undirected(self) -> "GraphFrame":
"""
Converts the directed graph into an undirected graph by ensuring that all directed edges are
bidirectional. For every directed edge (src, dst), a corresponding edge (dst, src) is added.
:return: A new GraphFrame representing the undirected graph.
"""
edge_attr_columns = [c for c in self.edges.columns if c not in [SRC, DST]]
# Create the undirected edges by duplicating each edge in both directions
# 3.5.x problem: selecting empty struct fails on spark connect
# TODO: remove after removing 3.5.x
if edge_attr_columns:
forward_edges = self.edges.select(
F.col(SRC), F.col(DST), F.struct(*edge_attr_columns).alias(EDGE)
)
backward_edges = self.edges.select(
F.col(DST).alias(SRC),
F.col(SRC).alias(DST),
F.struct(*edge_attr_columns).alias(EDGE),
)
new_edges = forward_edges.union(backward_edges).select(SRC, DST, EDGE)
else:
forward_edges = self.edges.select(F.col(SRC), F.col(DST))
backward_edges = self.edges.select(F.col(DST).alias(SRC), F.col(SRC).alias(DST))
new_edges = forward_edges.union(backward_edges).select(SRC, DST)
# Preserve additional edge attributes
edge_columns = [F.col(EDGE).getField(c).alias(c) for c in edge_attr_columns]
# Select all columns including the new edge attributes
selected_columns = [F.col(SRC), F.col(DST)] + edge_columns
new_edges = new_edges.select(*selected_columns)
return GraphFrame(self.vertices, new_edges)