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Last Modified: Nov 17, 2013
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In dlib, there are two types of graph representations. On the one
hand, there are graphs based on an object which encapsulates the whole
graph, such as the graph and
directed_graph objects. On the
other hand, there are graphs which are represented as simple vectors
of edges. In this case, we use vectors of sample_pair
or ordered_sample_pair objects for undirected
and directed graphs respectively.
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Graph Object Based Graphs Creating Edge List Based Graphs Using Edge List Based Graphs
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[top]copy_graph_structure
This function takes a
graph or
directed_graph and copies
its structure to another graph or directed_graph object. The only
restriction is that you can't copy the structure of a graph into a
directed_graph. The three other possible combinations are allowed
however.
#include <dlib/graph_utils.h>Detailed Documentation [top]cosine_distance
This is a simple function object that computes cosine of the angle between
two vectors.
#include <dlib/graph_utils.h>Detailed Documentation [top]create_join_tree
This function takes a
graph object and
creates a join tree for that graph. Or in other words, this function finds a
tree decomposition of the given graph.
#include <dlib/graph_utils.h>Detailed Documentation [top]find_approximate_k_nearest_neighbors
This function is a simple approximate form of
find_k_nearest_neighbors.
Instead of checking all possible edges it randomly samples a large number of them and then performs
exact k-nearest-neighbors on that randomly selected subset.
#include <dlib/graph_utils.h>Detailed Documentation [top]find_connected_nodes
This function takes a node from a
graph
or
directed_graph object and a
set of unsigned longs. It finds all the
nodes in the given graph that are connected to the given node by an
undirected path and returns them in the set (also note that the
original query node is also returned in this set).
#include <dlib/graph_utils.h>Detailed Documentation [top]find_neighbor_ranges
This function takes a graph, defined by a vector of
ordered_sample_pair objects, and finds the
ranges that contain the edges for each node in the graph. The output therefore
lets you easily locate the neighbors of any node in the graph.
#include <dlib/graph_utils.h>Detailed Documentation [top]graph_contains_length_one_cycle
This function takes a
graph
or
directed_graph object and
returns true if and only if the graph contains a node that has an edge that
links back to itself.
#include <dlib/graph_utils.h>Detailed Documentation [top]graph_has_symmetric_edges
This function checks if a
directed_graph
has a pair of nodes with just one edge between them. If so then it
does not have symmetric edges.
#include <dlib/graph_utils.h>Detailed Documentation [top]graph_is_connected
This function takes a
graph or
directed_graph object and
determines if the graph is connected. That is, it returns true if and only if
there is an undirected path between any two nodes in the given graph.
#include <dlib/graph_utils.h>Detailed Documentation [top]is_clique
This function takes a
graph and a
set of node index values and checks
if the specified set of nodes is a clique in the graph.
#include <dlib/graph_utils.h>Detailed Documentation [top]is_join_tree
This function takes two
graph objects and
checks if the second of the two graphs is a valid join tree (aka tree decomposition)
of the first graph.
#include <dlib/graph_utils.h>Detailed Documentation [top]is_maximal_clique
This function takes a
graph and a
set of node index values and checks
if the specified set of nodes is a maximal clique in the graph.
#include <dlib/graph_utils.h>Detailed Documentation [top]max_index_plus_one
This function finds the number that is one greater than the largest index
value in a std::vector of
sample_pair or
ordered_sample_pair objects. Therefore,
it is useful for finding out how many nodes are in an edge list graph (assuming
the graph contains all node indices from 0 to the largest index indicated
by an edge).
#include <dlib/graph_utils.h>Detailed Documentation [top]negative_dot_product_distance
This is a simple function object that computes -dot(v1,v2) for two
vectors v1 and v2.
#include <dlib/graph_utils.h>Detailed Documentation [top]ordered_sample_pair
This object is intended to represent an edge in a directed graph
which has data samples at its vertices. Therefore, it is the directed version
of
sample_pair.
#include <dlib/graph_utils.h>Detailed Documentation [top]order_by_descending_distance
This function provides a total ordering of
sample_pair
or
ordered_sample_pair objects that causes
pairs with largest distance to be the first in a sorted list. This function
can be used with std::sort().
#include <dlib/graph_utils.h>Detailed Documentation [top]order_by_distance_and_index
This function provides a total ordering of
sample_pair or
ordered_sample_pair objects that causes pairs
with smallest distance to be the first in a sorted list but also orders
samples with equal distances according to order_by_index(). This function
can be used with std::sort().
#include <dlib/graph_utils.h>Detailed Documentation [top]order_by_index
This function provides a total ordering of
sample_pair
or
ordered_sample_pair
objects that will cause pairs that represent the same edge to be adjacent
when sorted. So for example, this function can be used
with std::sort() to first sort a sequence of sample_pair objects and then
find duplicate edges.
#include <dlib/graph_utils.h>Detailed Documentation [top]triangulate_graph_and_find_cliques
This function takes a
graph and
turns it into a chordal graph. It also returns a
set that contains
all the cliques present in the chordal graph.
#include <dlib/graph_utils.h>Detailed Documentation [top]use_weights_of_one
This is a simple function object that takes a single argument
and always returns 1
#include <dlib/graph_utils.h>Detailed Documentation