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graphchi-cpp/example_apps/randomwalks.cpp at master · GraphChi/graphchi-cpp · GitHub
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randomwalks.cpp
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randomwalks.cpp
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/*
*
* @file
* @author Aapo Kyrola <akyrola@cs.cmu.edu>
* @version 1.0
*
* @section LICENSE
*
* Copyright [2012] [Aapo Kyrola, Guy Blelloch, Carlos Guestrin / Carnegie Mellon University]
*
* Licensed 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
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* @section DESCRIPTION
*
* Random walk simulation. From a set of source vertices, a set of
* random walks is started. Random walks walk via edges, and we use the
* dynamic chivectors to support multiple walks in one edge. Each
* vertex keeps track of the walks that pass by it, thus in the end
* we have estimate of the "pagerank" of each vertex.
*
* Note, this version does not support 'resets' of random walks.
* TODO: from each vertex, start new random walks with some probability,
* and also terminate a walk with some probablity.
*
*/
#
define
DYNAMICEDATA
1
#
include
<
string
>
#
include
"
graphchi_basic_includes.hpp
"
#
include
"
api/dynamicdata/chivector.hpp
"
#
include
"
util/toplist.hpp
"
using
namespace
graphchi
;
/*
*
* Type definitions. Remember to create suitable graph shards using the
* Sharder-program.
*/
typedef
unsigned
int
VertexDataType;
typedef
chivector<
vid_t
> EdgeDataType;
struct
RandomWalkProgram
:
public
GraphChiProgram
<VertexDataType, EdgeDataType> {
int
walks_per_source
() {
return
100
;
}
bool
is_source
(
vid_t
v) {
return
(v %
50
==
0
);
}
/*
*
* Vertex update function.
*/
void
update
(graphchi_vertex<VertexDataType, EdgeDataType > &vertex, graphchi_context &gcontext) {
if
(gcontext.
iteration
==
0
) {
if
(
is_source
(vertex.
id
())) {
for
(
int
i=
0
; i <
walks_per_source
(); i++) {
/*
Get random out edge's vector
*/
graphchi_edge<EdgeDataType> * outedge = vertex.
random_outedge
();
if
(outedge !=
NULL
) {
chivector<
vid_t
> * evector = outedge->
get_vector
();
/*
Add a random walk particle, represented by the vertex-id of the source (this vertex)
*/
evector->
add
(vertex.
id
());
gcontext.
scheduler
->
add_task
(outedge->
vertex_id
());
//
Schedule destination
}
}
}
vertex.
set_data
(
0
);
}
else
{
/*
Check inbound edges for walks and advance them.
*/
int
num_walks =
0
;
for
(
int
i=
0
; i < vertex.
num_inedges
(); i++) {
graphchi_edge<EdgeDataType> * edge = vertex.
inedge
(i);
chivector<
vid_t
> * invector = edge->
get_vector
();
for
(
int
j=
0
; j < invector->
size
(); j++) {
/*
Get one walk
*/
vid_t
walk = invector->
get
(j);
/*
Move to a random out-edge
*/
graphchi_edge<EdgeDataType> * outedge = vertex.
random_outedge
();
if
(outedge !=
NULL
) {
chivector<
vid_t
> * outvector = outedge->
get_vector
();
/*
Add a random walk particle, represented by the vertex-id of the source (this vertex)
*/
outvector->
add
(walk);
gcontext.
scheduler
->
add_task
(outedge->
vertex_id
());
//
Schedule destination
}
num_walks ++;
}
/*
Remove all walks from the inbound vector
*/
invector->
clear
();
}
/*
Keep track of the walks passed by via this vertex
*/
vertex.
set_data
(vertex.
get_data
() + num_walks);
}
}
/*
*
* Called before an iteration starts.
*/
void
before_iteration
(
int
iteration, graphchi_context &gcontext) {
}
/*
*
* Called after an iteration has finished.
*/
void
after_iteration
(
int
iteration, graphchi_context &gcontext) {
}
/*
*
* Called before an execution interval is started.
*/
void
before_exec_interval
(
vid_t
window_st,
vid_t
window_en, graphchi_context &gcontext) {
}
/*
*
* Called after an execution interval has finished.
*/
void
after_exec_interval
(
vid_t
window_st,
vid_t
window_en, graphchi_context &gcontext) {
}
};
int
main
(
int
argc,
const
char
** argv) {
/*
GraphChi initialization will read the command line
arguments and the configuration file.
*/
graphchi_init
(argc, argv);
/*
Metrics object for keeping track of performance counters
and other information. Currently required.
*/
metrics
m
(
"
randomwalk
"
);
/*
Basic arguments for application
*/
std::string filename =
get_option_string
(
"
file
"
);
//
Base filename
int
niters =
get_option_int
(
"
niters
"
,
4
);
//
Number of iterations
bool
scheduler =
true
;
//
Whether to use selective scheduling
/*
Detect the number of shards or preprocess an input to create them
*/
bool
preexisting_shards;
int
nshards = convert_if_notexists<
vid_t
>(filename,
get_option_string
(
"
nshards
"
,
"
auto
"
), preexisting_shards);
/*
Run
*/
RandomWalkProgram program;
graphchi_engine<VertexDataType, EdgeDataType>
engine
(filename, nshards, scheduler, m);
if
(preexisting_shards) {
engine.
reinitialize_edge_data
(
0
);
}
engine.
run
(program, niters);
/*
List top 20
*/
int
ntop =
20
;
std::vector< vertex_value<VertexDataType> > top = get_top_vertices<VertexDataType>(filename, ntop);
std::cout <<
"
Print top 20 vertices:
"
<< std::endl;
for
(
int
i=
0
; i < (
int
) top.
size
(); i++) {
std::cout << (i+
1
) <<
"
.
"
<< top[i].
vertex
<<
"
\t
"
<< top[i].
value
<< std::endl;
}
/*
Report execution metrics
*/
metrics_report
(m);
return
0
;
}
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