Graph Tools
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.
order_by_index
dlib/graph_utils.h
dlib/graph_utils/sample_pair_abstract.h
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.
order_by_distance
dlib/graph_utils.h
dlib/graph_utils/sample_pair_abstract.h
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. This function
can be used with std::sort().
order_by_descending_distance
dlib/graph_utils.h
dlib/graph_utils/sample_pair_abstract.h
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().
order_by_distance_and_index
dlib/graph_utils.h
dlib/graph_utils/sample_pair_abstract.h
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().
contains_duplicate_pairs
dlib/graph_utils.h
dlib/graph_utils/edge_list_graphs_abstract.h
This function checks if a std::vector of sample_pair or
ordered_sample_pair objects
contains any edge more than once.
max_index_plus_one
dlib/graph_utils.h
dlib/graph_utils/edge_list_graphs_abstract.h
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).
sample_pair
dlib/graph_utils.h
dlib/graph_utils/sample_pair_abstract.h
This object is intended to represent an edge in an undirected graph
which has data samples at its vertices. Therefore, it is the undirected version
of ordered_sample_pair.
linear_manifold_regularizer_ex.cpp.html
ordered_sample_pair
dlib/graph_utils.h
dlib/graph_utils/ordered_sample_pair_abstract.h
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.
find_percent_shortest_edges_randomly
dlib/graph_utils.h
dlib/graph_utils/edge_list_graphs_abstract.h
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 returns the best ones.
linear_manifold_regularizer_ex.cpp.html
find_k_nearest_neighbors
dlib/graph_utils.h
dlib/graph_utils/edge_list_graphs_abstract.h
This is a function which finds all the k nearest neighbors of a set of points and outputs
the result as a vector of sample_pair objects. It takes O(n^2) time where
n is the number of data samples. A faster approximate version is provided by
find_approximate_k_nearest_neighbors
and find_k_nearest_neighbors_lsh.
find_k_nearest_neighbors_lsh
dlib/graph_utils_threaded.h
dlib/graph_utils/find_k_nearest_neighbors_lsh_abstract.h
This function is a simple approximate form of find_k_nearest_neighbors.
It uses locality sensitive hashing
to speed up the nearest neighbor computation and is also capable of using a multi-core CPU.
find_approximate_k_nearest_neighbors
dlib/graph_utils.h
dlib/graph_utils/edge_list_graphs_abstract.h
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.
remove_short_edges
dlib/graph_utils.h
dlib/graph_utils/edge_list_graphs_abstract.h
This is a simple function for removing edges with a small distance value from
a vector of sample_pair or ordered_sample_pair objects.
remove_duplicate_edges
dlib/graph_utils.h
dlib/graph_utils/edge_list_graphs_abstract.h
This is a simple function for removing duplicate edges (i.e. edges that compare equal
according to ==) from
a vector of sample_pair or ordered_sample_pair objects.
remove_long_edges
dlib/graph_utils.h
dlib/graph_utils/edge_list_graphs_abstract.h
This is a simple function for removing edges with a large distance value from
a vector of sample_pair or ordered_sample_pair objects.
remove_percent_longest_edges
dlib/graph_utils.h
dlib/graph_utils/edge_list_graphs_abstract.h
This is a simple function for removing edges with a large distance value from
a vector of sample_pair or ordered_sample_pair objects.
remove_percent_shortest_edges
dlib/graph_utils.h
dlib/graph_utils/edge_list_graphs_abstract.h
This is a simple function for removing edges with a small distance value from
a vector of sample_pair or ordered_sample_pair objects.
squared_euclidean_distance
dlib/graph_utils.h
dlib/graph_utils/function_objects_abstract.h
This is a simple function object that computes squared euclidean distance
between two matrix objects.
linear_manifold_regularizer_ex.cpp.html
cosine_distance
dlib/graph_utils.h
dlib/graph_utils/function_objects_abstract.h
This is a simple function object that computes cosine of the angle between
two vectors.
negative_dot_product_distance
dlib/graph_utils.h
dlib/graph_utils/function_objects_abstract.h
This is a simple function object that computes -dot(v1,v2) for two
vectors v1 and v2.
use_weights_of_one
dlib/graph_utils.h
dlib/graph_utils/function_objects_abstract.h
This is a simple function object that takes a single argument
and always returns 1
use_gaussian_weights
dlib/graph_utils.h
dlib/graph_utils/function_objects_abstract.h
This is a simple function object that takes a single argument
which should be an object similar to sample_pair.
linear_manifold_regularizer_ex.cpp.html
is_ordered_by_index
dlib/graph_utils.h
dlib/graph_utils/edge_list_graphs_abstract.h
This function checks if a vector of sample_pair or
ordered_sample_pair objects is in sorted
order according to their index values.
find_neighbor_ranges
dlib/graph_utils.h
dlib/graph_utils/edge_list_graphs_abstract.h
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.
convert_unordered_to_ordered
dlib/graph_utils.h
dlib/graph_utils/edge_list_graphs_abstract.h
This function takes a graph, defined by a vector of
sample_pair objects and converts it into the equivalent
graph defined by a vector of ordered_sample_pair objects.
edge
dlib/graph_utils.h
dlib/graph_utils/graph_utils_abstract.h
This function takes a graph or
directed_graph object and a
pair of indices. It returns a reference to the edge object between the two nodes
with the given indices.
is_join_tree
dlib/graph_utils.h
dlib/graph_utils/graph_utils_abstract.h
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.
create_join_tree
dlib/graph_utils.h
dlib/graph_utils/graph_utils_abstract.h
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.
graph_contains_directed_cycle
dlib/graph_utils.h
dlib/graph_utils/graph_utils_abstract.h
This function checks a directed_graph for directed cycles.
graph_has_symmetric_edges
dlib/graph_utils.h
dlib/graph_utils/graph_utils_abstract.h
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.
triangulate_graph_and_find_cliques
dlib/graph_utils.h
dlib/graph_utils/graph_utils_abstract.h
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.
create_moral_graph
dlib/graph_utils.h
dlib/graph_utils/graph_utils_abstract.h
This function takes a directed_graph
and returns the moralized version of the graph in the form of a
graph object.
graph_contains_length_one_cycle
dlib/graph_utils.h
dlib/graph_utils/graph_utils_abstract.h
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.
find_connected_nodes
dlib/graph_utils.h
dlib/graph_utils/graph_utils_abstract.h
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).
graph_is_connected
dlib/graph_utils.h
dlib/graph_utils/graph_utils_abstract.h
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.
is_clique
dlib/graph_utils.h
dlib/graph_utils/graph_utils_abstract.h
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.
copy_graph
dlib/graph_utils.h
dlib/graph_utils/graph_utils_abstract.h
This function takes a graph or
directed_graph and
makes a copy of it.
copy_graph_structure
dlib/graph_utils.h
dlib/graph_utils/graph_utils_abstract.h
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.
is_maximal_clique
dlib/graph_utils.h
dlib/graph_utils/graph_utils_abstract.h
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.
graph_contains_undirected_cycle
dlib/graph_utils.h
dlib/graph_utils/graph_utils_abstract.h
This function checks a directed_graph for undirected cycles.