I wrote a shortest path code in Graphchi and I wanted to print the output of that in a file. I was trying to use the template shown in the examples but I get error if I use the sameway of writing to a file as in other examples.
I have got stuck here. As the output I just want to print (vertex id,its minimum distance from source).
How can i do that.
Here is example how you can output values of all vertices to the console. It is easy to modify it to write the output to a file. Note that if you can handle binary files, GraphChi already has the vertex values in a file: .B.vout, where is sizeof(VertexDataType).
1) You need to define a callback-function, which will take vertex id and value as parameter
class OutputVertexCallback : public VCallback<VertexDataType> {
public:
virtual void callback(vid_t vertex_id, VertexDataType &value) {
std::cout << vertex_id << "=" << value << std::endl;
}
};
2) Then you need to call foreach_vertices() as follows to get the output:
OutputVertexCallback callback;
foreach_vertices<VertexDataType>(filename, 0, engine.num_vertices(), callback);
Related
Although I don't know how to write C++ I am trying to use CGAL for trying to derive building shapes from LiDAR point clouds using Point Set Shape Detection. Using the examples I can read points and normals from a file, whereupon CGAL detects shapes. The program is set to detect only planar shapes.
I would like to save the planar shapes to a file, so that I can use them in other software. But I was unable to find examples of how that can be achieved. The test program I use is based on the efficient_RANSAC_parameters.cpp code. It has a part when it iterates through all detected shapes. Could it be possible to add something there that will write the planar shapes to a file? I see the OFF format is a popular and simple way (in CGAL) to save polygons to a file, so that could be a good candidate file format.
A colleague who does know how to write C++ has helped me with this problem. He came up with the following:
while (it != shapes.end()) {
if (Plane* plane = dynamic_cast<Plane*>(it->get()))
{
std::cout << "PLANE_" << count++ << "[" << std::endl;
const std::vector<size_t> indices = it->get()->indices_of_assigned_points();
std::vector<size_t>::const_iterator iti = indices.begin();
while (iti != indices.end()) {
// Retrieves point
Point_with_normal pw = *(points.begin() + (*iti));
Kernel::Point_3 p = pw.first;
std::cout << "POINT[" << p.x() << "," << p.y() << "," << p.z() << "]" << std::endl;
// Proceeds with next point.
iti++;
}
std::cout << "]" << std::endl;
}
// Proceeds with next detected shape.
it++;
}
This block can replace loop in the efficient_RANSAC_parameters.cpp example. The output looks like this:
PLANE_0[
POINT[34.96,584.49,0.47]
POINT[34.97,585.24,0.54]
POINT[34.88,584.51,0.49]
POINT[34.98,584.75,0.49]
]
That gives me something to work with. In my case, I use sed to transform this output to SQL insert queries that allow me to transfer the data to a relational database for further processing.
In the example in the user manual you can see that once you have a plane shape object
if(Plane* plane = dynamic_cast<Plane*>(it->get())){..} you can obtain from the plane shape object a CGAL::Plane_3, from which you can obtain a point and a normal, or the coefficients of the plane.
How I will be able to get the int representation in Galois Field using NTL library. For example of element
GF2E xx=random_GF2E();
I'm trying use
printf("%d",xx._GF2E__rep.HexOutput);
but I get 0
GF2E is an extension field, i.e. the elements in GF2E are living in GF(2)[X]/(P), where P is an irreducable polynomial. So you can not get an integer representation. But you can get a representation as a vector.
GF2X P;
SetCoeff(P, 0, 1);
SetCoeff(P, 1, 1);
SetCoeff(P, 2, 1);
// P is now x^2+x+1, this is irreducable since P(1)=1 and P(0)=1
GF2E::init(P);
GF2E xx = random_GF2E();
cout << xx << endl; // Prints something like "[0 1]"
Notice: To use this code snippet, you have to import the namespaces NTL and std to your programm by using using namespace NTL; and using namespace std; after your includes.
An other way would be to add NTL:: to all the NTL functions and std:: to cout and endl.
See this tutorial for more information about namespaces.
So I have the following grammar:
top_cmd :cmds
{
std::cout << $cmds.text << std::endl;
}
;
cmds returns [char* str]
: cmd+
{
str = new char('a');
}
;
I get g++ compile error:
"str" was not declared in this scope
If I remove this line
std::cout << $cmds.text << std::endl;
Then compile is fine.
I googled how "$text" is used, it seems to me it is expected to use $text for the purpose of rewrite rules. In my example, the function "cmds" returns "char*" when I remove the offending line and some complex structure when I keep it.
I can think of the following workaround:
1. do not have lower level rules return anything, but pass variable into lower level rules.
2. use re-write rules
But both are pretty big change(my real project is fairly large) considering how much time budge I have.
So is there a short-cut? Basically I do not want to change the grammar of top_cmd and cmds, but I can get the full text of cmds' matching.
I am using ANTLR3C, but I believe this is independent of target language.
I think you should do something like this:
top_cmd :cmds
{
std::cout << $cmds.text << std::endl;}
;
cmds returns [char* str]
: cmd+
{
$str = new char('a'); //added $
}
;
$cmds.text will return the text matched for the rule cmds. If you want to return the str, you should change it for $cmds.str
$text: The text matched for a rule or the text matched
from the start of the rule up until the point of
the $text expression evaluation. Note that this
includes the text for all tokens including those
on hidden channels, which is what you want
because usually that has all the whitespace and
comments. When referring to the current rule,
this attribute is available in any action including
any exception actions.
from the Definitive Antrl reference
I had read this page , http://llvm.org/docs/WritingAnLLVMPass.html
And i can do the example of the Hello.so completely.
Now i just want to make a .so file that can be called by opt and read my IR file name as input argument. And after i commit it , it will output the name of the file.
I had tried several methods before , but i still don't know how to do it....
I hope i can do it like this.
opt -load ../Debug+Asserts/lib/xxxx.so -flag < llvm.ll > /dev/null
when i press ENTER , it will output the name of the file -> "llvm.ll"
Can anyone help me write this simple program , i am going to optimize the llvm IR as my semester project , and now i stuck here ... help me , thanks ~
Can you tell me the code in detail , this doesn't work for me
using namespace llvm;
namespace {
struct Hello : public ModulePass {
static char ID;
Hello() : ModulePass(ID) {}
virtual bool runOnModule(Module &M) {
dbgs() << M.getModuleIdentifier() << "\n";
return false;
}
};
}
char Hello::ID = 0;
static RegisterPass<Hello> X("hello", "Hello World Pass", false, false);
~
Your question could really be simplified to "how can I access the name of the current .ll file from within an LLVM pass". You don't need to "parse LLVM IR" or anything like that - when an LLVM pass is being ran it is already way past the parsing phase.
In any case, I'm not aware of any surefire way to get the filename from an LLVM module, but you can encode that information when you prepare the .ll file. For example, set the module id to be the filename via ; ModuleID = 'llvm.ll', then retrieve it by writing a module pass and invoking getModuleIdentifier to get the string. Then you could just print it out, e.g.
bool runOnModule(Module& M) {
dbgs() << M.getModuleIdentifier() << "\n";
return false;
}
Alternatively, use metadata.
I find this example:
ofstream ofstr("output.yaml");
YAML::Emitter out(ofstr);
out << some_large_document;
// not necessary anymore:
// ofstr << out.c_str()
But when i try use it, i have:
D:\work\C\map.cpp||In function `int main()':|
D:\work\C\map.cpp|24|error: no matching function for call to `YAML::Emitter::Emitter(std::ofstream&)'|
D:\work\C\yaml-cpp\emitter.h|23|note: candidates are: YAML::Emitter::Emitter(YAML::Emitter&)|
D:\work\C\yaml-cpp\emitter.h|25|note: YAML::Emitter::Emitter()|
||=== Build finished: 1 errors, 0 warnings ===|
There's no constructor to YAML::Emitter that takes a stream. (Where did you find that example?)
Instead, you do need to use the commented out line:
ofstream ofstr("output.yaml");
YAML::Emitter out;
out << some_large_document;
ofstr << out.c_str(); // is necessary!