https://github.com/vikram-ma/OCR
when I try to run main.cpp from this code i got the following error
In file included from /home/akash/Desktop/OCR-master/main.cpp:9:0:
/home/akash/Desktop/OCR-master/OCR.h:43:3: error: ‘CvKNearest’ does not name a type
CvKNearest *knn;
^
CMakeFiles/OCR.dir/build.make:62: recipe for target 'CMakeFiles/OCR.dir/main.o' failed
please help
At first glance it seems you don't have OpenCV installed/downloaded.
The code you are poining to uses OpenCV library and it assumes you already have it.
You should go to OpenCV releases and download the version you need.
Edit:
I looked into it more closely and as suspected the code was using an old OpencCV version. Right now you are using 3.2.0 so you need to make some updates to the code itself.
Either you should go with an older version of the library (which I'm not suggesting but will be probably less effort) like 2.3-2.4 or update the code to the version you've already installed.
If you wish to do the latter, you can start by looking here: Transition guide
Among others, it is shown there that what used to be CvKNearest is now moved to cv::ml::KNearest. Updating accordingly should fix your first error.
I'm trying to write unit tests using miniDFSCluster and it's throwing the error below
java.lang.UnsatisfiedLinkError: org.apache.hadoop.io.nativeio.NativeIO$Windows.access0(Ljava/lang/String;I)Z
any pointers to resolve this issue?
With errors like this, I use three steps
Find out what it is looking for
In this case, *org.apache.hadoop.io.nativeio.NativeIO$Windows.access0*
Find out what jar/lib it is in.
I don't use the Windows version, but I believe it is in hadoop.dll -
you'll have to check this.
Find out where I'm telling it to use that jar/lib
Update: See also this Answer.
I was able to resolve this error by following these steps:
Download hadoop.dll and winutils.exe in the same version that I'm using in the sbt/maven configuration, you can find these files in all versions of hadoop here: link
Put these 2 files in your %hadoop directory%\bin folder
make sure that %hadoop directory%\bin is listed under PATH in your device's environmental path(if using windows)
then the code should work just fine.
We are using an environment variable to specify a path to a library we use. Most of the time it points to the released version but sometimes to a development version.
Anyway, it works ok when I use $(MyLib)/path;%(AdditionalIncludeDirectories) for building the C++ application but I can not open the project resources. However, when I use %(MyLib)/path;%(AdditionalIncludeDirectories) it works.
Now, what is the difference?
I thought the correct way is to use $(EnvVar) but for the resource editor it doesn't seems to work. And if $(EnvVar) is the correct way then why does Visual Studio use %(AdditionalIncludeDirectories) and not $(AdditionalIncludeDirectories)
The error I get is: fatal error RC1015: cannot open include file 'afxres.h'.
You use %(item) to refer to an MSBuild metadata item. Using $(AdditionalIncludeDirectories) would not work well if you also had an environment variable by that name. So %(MyLib)/path ought to resolve to just /path.
You can put echo %(MyLib)/path in a prebuild event to verify this.
Which is probably enough to stop confusing rc.exe, the resource compiler. Which is a stone-cold-old SDK utility, going back all the way to Windows version 1.0. It is pretty temperamental, very picky about command line options and .rc script file text encoding. Do keep in mind that it dates from an era long before Windows started to support a forward slash as a path separator, everybody had to use a backslash back in 1986.
So use "$(MyLib)\path" instead, including the double quotes so you don't confuzzle it when MyLib contains embedded spaces. And do favor using a project property sheet instead so there are some odds that somebody can still figure out how to get the project built correctly 2+ years from now.
I currently have a .cpp file that I can compile using sourceCpp(). As expected the corresponding R function is created and the code works as expected.
Here it is:
#include <Rcpp.h>
using namespace Rcpp;
// [[Rcpp::export]]
NumericVector exampleOne(NumericVector vectorOne, NumericVector vectorTwo){
NumericVector outputVector = vectorOne + vectorTwo;
return outputVector;
}
I am now converting my project over to a package using Rcpp. So I created the skeleton with rStudio and started looking at how to convert things over.
In Hadley's excellent primer on Cpp, he says in section "Using Rcpp in a Package":
If your packages uses the Rcpp::export attribute then one additional step in the package build process is requried. The compileAttributes function scans the source files within a package for Rcpp::export attributes and generates the code required to export the functions to R.
You should re-run compileAttributes whenever functions are added, removed, or have their signatures changed. Note that if you build your package using RStudio or devtools then this step occurs automatically.
So it looks like the code that compiled with sourceCpp() should work pretty much as is in a package.
I created the corresponding R file.
exampleOne <- function(vectorOne, vectorTwo){
outToR <- .Call("exampleOne", vectorOne, vectorTwo, PACKAGE ="testPackage")
outToR
}
Then I (re)built the package and I get this error:
Error in .Call("exampleOne", vectorOne, vectorTwo, PACKAGE = "voteR") :
C symbol name "exampleOne" not in DLL for package "testPackage"
Does anyone have an idea as to what else I need to do when taking code that compiles with sourceCpp() and then using it in a package?
I should note that I have read: "Writing a package that uses Rcpp" http://cran.rstudio.com/web/packages/Rcpp/vignettes/Rcpp-package.pdf and understand the basic structure presented there. However, after looking at the RcppExamples source code, it appears that the structure in the vignettes is not exactly the same as that used in the example package. For example there are no .h files used. Also neither the vignette nor the source code use the [[Rcpp::export]] attribute. This all makes it difficult to track down exactly where my error is.
Here is my "walk through" of how to go from using sourceCpp() to a package that uses Rcpp. If there is an error please feel free to edit this or let me know and I will edit it.
[NOTE: I HIGHLY recommend using RStudio for this process.]
So you have the sourceCpp() thing down pat and now you need to build a package. This is not hard, but can be a bit tricky, because the information out there about building packages with Rcpp ranges from the exhaustive thorough documentation you want with any R package (but that is above your head as a newbie), and the newbie sensitive introductions (that may leave out a detail you happen to need).
Here I use oneCpp.cpp and twoCpp.cpp as the names of two .cpp files you will use in your package.
Here is what I suggest:
A. First I assume you have a version of theCppFile.cpp that compiles with sourceCpp() and works as you expect it to. This is not a must, but if you are new to Rcpp OR packages, it is nice to make sure your code works in this simple situation before you move to the more complicated case below.
B. Now build your package using Rcpp.package.skeleton() or use the Project>Create Project>Package w/Rcpp wizard in RStudio (HIGHLY recommended). You can find details about using Rcpp.package.skeleton() in hadley/devtools or Rcpp Attributes Vignette. The full documentation for writing packages with Rcpp is in Writing a package that uses Rcpp, however this one assumes you know your way around C++ fairly well, and does not use the new "Attributes" way of doing Rcpp. It will be invaluable though if you move toward making more complex packages.
You should now have a directory structure for your package that looks something like this:
yourPackageName
- DESCRIPTION
- NAMESPACE
- \R\
- RcppExports.R
- Read-and-delete-me
- \man\
- yourPackageName-package.Rd
- \src\
- Makevars
- Makevars.win
- oneCpp.cpp
- twoCpp.cpp
- RcppExports.cpp
Once everything is set up, do a "Build & Reload" if using RStudio, or compileAttributes() if you are not in RStudio.
C. You should now see in your \R directory a file called RcppExports.R. Open it and check it out. In RcppExports.R you should see the R wrapper functions for all the .cpp files you have in your \src directory. Pretty sweet, eh?.
D) Try out the R function that corresponds to the function you wrote in theCppFile.cpp. Does it work? If so move on.
E) You can now just add new .cpp files like otherCpp.cpp to the \src directory as you create them. Then you just have to rebuild the package, and the R wrappers will be generated and added to RcppExports.R for you. In RStudio this is just "Build & Reload" in the Build menu. If you are not using RStudio you should run compileAttributes()
In short, the trick is to call compileAttributes() from within the root of the package. So for instance for package foo
$ cd /path/to/foo
$ ls
DESCRIPTION man NAMESPACE R src
$ R
R> compileAttributes()
This command will generate the RcppExports.cpp and RcppExports.R that were missing.
You are missing the forest for the trees.
sourceCpp() is a recent function; it is part of what we call "Rcpp attributes" which has its own vignette (with the same title, in the package, on my website, and on CRAN) which you may want to read. It among other things details how to turn something you compiled and run using sourceCpp() into a package. Which is what you want.
Randomly jumping between documentation won't help you, and at the end of the genuine source documentation by package authors may be preferable. Or to put a different spin on it: you are using a new feature but old documentation that doesn't reflect it. Try to write a basic package with Rcpp, ie come to it from the other end as well.
Lastly, there is a mailing list...
How to get from C/C++ extension source code to a pyd file for windows (or other item that I could import to Python)?
edit: The specific library that I wanted to use (BRISK) was included in OpenCV 2.4.3 so my need for this skill went away for the time being. In case you came here looking for BRISK, here is a simple BRISK in Python demo that I posted.
I have the Brisk source code (download) that I would like to build and use in my python application. I got as far as generating a brisk.pyd file... but it was 0 bytes. If there is a better / alternative way to aiming for a brisk.pyd file, then of course I am open to that as well.
edit: Please ignore all the attempts in my original question below and see my answer which was made possible by obmarg's detailed walkthrough
Where am I going wrong?
Distutils without library path: First I tried to build the source as is with distutils and the following setup.py (I have just started learning distutils so this is a shot in the dark). The structure of the BRISK source code is at the bottom of this question for reference.
from distutils.core import setup, Extension
module1 = Extension('brisk',
include_dirs = ['include', 'C:/opencv2.4/build/include', 'C:/brisk/thirdparty/agast/include'],
#libraries = ['agast_static', 'brisk_static'],
#library_dirs = ['win32/lib'],
sources = ['src/brisk.cpp'])
setup (name = 'BriskPackage',
ext_modules = [module1])
That instantly gave me the following lines and a 0 byte brisk.pyd somewhere in the build folder. So close?
running build
running build_ext
Distutils with library path: Scratch that attempt. So I added the two library lines that are commented out in the above setup.py. That seemed to go ok until I got this linking error:
creating build\lib.win32-2.7
C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\BIN\link.exe /DLL /nologo /INCREMENTAL:NO /LIBPATH:win32/lib /LIB
PATH:C:\Python27_32bit\libs /LIBPATH:C:\Python27_32bit\PCbuild agast_static.lib brisk_static.lib /EXPORT:initbrisk build
\temp.win32-2.7\Release\src/brisk.obj /OUT:build\lib.win32-2.7\brisk.pyd /IMPLIB:build\temp.win32-2.7\Release\src\brisk.
lib /MANIFESTFILE:build\temp.win32-2.7\Release\src\brisk.pyd.manifest
LINK : error LNK2001: unresolved external symbol initbrisk
build\temp.win32-2.7\Release\src\brisk.lib : fatal error LNK1120: 1 unresolved externals
error: command '"C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\BIN\link.exe"' failed with exit status 1120
Uncontrolled flailing: I thought maybe the libraries needed to be built, so I did a crash course (lots of crashing) with cmake + mingw - mingw + vc++ express 2010 as follows:
cmake gui: source: c:/brisk, build: c:/brisk/build
cmake gui: configure for Visual Studio 10
cmake gui: use default options and generate (CMAKE_BACKWARDS_COMPATIBILITY, CMAKE_INSTALL_PREFIX, EXECUTABLE_OUTPUT_PATH, LIBRARY_OUTPUT_PATH)
VC++ Express 10: Change to Release and build the solution generated by cmake and get about 20 pages of what look like non-critical warnings followed by all succeeded. Note - no dlls are generated by this. It does generate the following libraries of similar size to the ones included with the download:
win32/lib/Release/
agast_static.lib
brisk_static.lib
Further flailing.
Relevant BRISK source file structure for reference:
build/ (empty)
include/brisk/
brisk.h
hammingsse.hpp
src
brisk.cpp
demo.cpp
thirdparty/agast/
include/agast/
agast5_8.h ....
cvWrapper.h
src/
agast5_8.cc ...
CMakeLists.txt
win32/
bin/
brisk.mexw32
opencv_calib3d220.dll ...
lib/
agast_static.lib
brisk_static.lib
CMakeLists.txt
FindOpenCV.cmake
Makefile
Are you sure that this brisk library even exports python bindings? I can't see any reference to it in the source code - it doesn't even seem to import python header files. This would certainly explain why you've not had much success so far - you can't just compile plain C++ code and expect python to interface with it.
I think your second distutils example is closest to correct - it's obviously compiling things and getting to the linker stage, but then you encounter this error. That error just means it can't find a function named initbrisk which I'm guessing would be the top level init function for the module. Again this suggests that you're trying to compile a python module from code that isn't meant for it.
If you want to wrap the C++ code in a python wrapper yourself you could have a look at the official documentation on writing c/c++ extensions. Alternatively you could have a look into boost::python, SIP or shiboken which try to somewhat (or completely) automate the process of making python extensions from C++ code.
EDIT: Since you seem to have made a decent amount of effort to solve the problem yourself and have posted a good question, I've decided to give a more detailed response on how to go about doing this.
Quick Tutorial On Wrapping C++ Libraries Using boost::python
Personally I've only ever used boost::python for stuff like this, so I'll try and give you a good summary of how to go about doing that. I'm going to assume that you're using Visual C++ 2010. I'm also going to assume that you've got a 32bit version of python installed, as I believe the boost pro libraries only provide 32bit binaries.
Installing boost
First you'll need to grab a copy of the boost library. The easiest way to do this is to download an installer from the boost pro website. These should install all the header files and binary files that are required for using the boost c++ library on windows. Take note of where you install these files to, as you'll need them later on - it might be best to install to a path without a space in it. For easyness I'm going to assume you put these files in C:\boost but you can substitute that for the path you actually used.
Alternatively, you can follow these instructions to build boost from source. I'm not 100% sure, but it might be the case that you need to do this in order to get a version of boost::python that is compatible with the version of python you have installed.
Setting up a visual studio project
Next, you'll want to setup a visual studio project for brisk.pyd. If you open visual studio, go to New -> Project then find the option for Win32 Project. Set up your location etc. and click ok. In the wizard that appears select a DLL project type, and then tick the empty project checkbox.
Now that you've created your project, you'll need to set up the include & library paths to allow you to use python, boost::python and the brisk.lib file.
In Visual Studios solution explorer, right click on your project, and select properties from the menu that appears. This should open up the property pages for your project. Go to the Linker -> General section and look for the Additional Library Directories section. You'll need to fill this in with the paths to the .lib files for boost, python and your brisk_static.lib. Generally these can be found in lib (or libs) subdirectories of
wherever you've installed the libraries. Paths are seperated with semicolons. I've attached a screenshot of my settings below:
Next, you'll need to get visual studio to link to the .lib files. These sections can be found in the Additional Dependencies field of the Linker -> Input section of the properties. Again it's a semicolon delimited list. You should need to add in libraries for python (in my case this is python27.lib but this will vary by version) and brisk_static.lib. These do not require the full path as you added that in the previous stage. Again, here's a screenshot:
You may also need to add the boost_python library file but I think boost uses some header file magic to save you the trouble. If I'm incorrect then have a look in you boost library path for a file named similar to boost_python-vc100-mt.lib and add that in.
Finally, you'll need to setup the include paths to allow your project to include the relevant C++ header files. To get the relevant settings to appear in project properties, you'll need to add a .cpp file to your project. Right click the source files folder in your solution explorer, and then go to add new item. Select a C++ File (.cpp) and name it main.cpp (or whatever else you want).
Next, go back to your project properties and go to C/C++ -> General. Under the additional libraries directory you need to add the include paths for brisk, python and boost. Again, semicolons for seperators, and again here's a screenshot:
I suspect that you might need to update these settings to include the opencv2 & agast libraries as well but I'll leave that as a task for you to figure out - it should be much the same process.
Wrapping existing c++ classes with boost::python.
Now comes the slightly trickier bit - actually writing C++ to wrap your brisk library in boost python. You can find a tutorial for this here but i'll try and go over it a bit as well.
This will be taking place in the main.cpp file you created earlier. First, add the relevant include statements you'll need at the top of the file:
#include <brisk/brisk.h>
#include <Python.h>
#include <boost/python.hpp>
Next, you'll need to declare your python module. I'm assuming you'd want this to be called brisk, so you do something like this:
BOOST_PYTHON_MODULE(brisk)
{
}
This should tell boost::python to create a python module named brisk.
Next it's just a case of going through all the classes & structs that you want to wrap and declaring boost python classes with them. The declerations of the classes should all be contained in brisk.h. You should only wrap the public members of a class, not any protected or private members. As a quick example, I've done a couple of the structs here:
BOOST_PYTHON_MODULE(brisk)
{
using namespace boost::python;
class_< cv::BriskPatternPoint >( "BriskPatternPoint" )
.def_readwrite("x", &cv::BriskPatternPoint::x)
.def_readwrite("y", &cv::BriskPatternPoint::y)
.def_readwrite("sigma", &cv::BriskPatternPoint::sigma);
class< cv::BriskScaleSpace >( "BriskScaleSpace", init< uint8_t >() )
.def( "constructPyramid", &cv::BriskScaleSpace::constructPyramid );
}
Here I have wrapped the cv::BriskPatternPoint structure and the cv::BriskScaleSpace class. Some quick explanations:
class_< cv::BriskPatternPoint >( "BriskPatternPoint" ) tells boost::python to declare a class, using the cv::BriskPatternPoint C++ class, and expose it as BriskPatternPoint in python.
.def_readwrite("y", &cv::BriskPatternPoint::y) adds a readable & writeable property to the BriskPatternPoint class. The property is named y, and will map to the BriskPatternPoint::y c++ field.
class< cv::BriskScaleSpace >( "BriskScaleSpace", init< uint8_t >() ) declares another class, this time BriskScaleSpace but also provides a constructor that accepts a uint8_t (an unsigned byte - which should just map to an integer in python, but I'd be careful to not pass in one greater than 255 bytes - I don't know what would happen in that situation)
The following .def line just declares a function - boost::python should (I think) be able to determine the argument types of functions automatically, so you don't need to provide them.
It's probably worth noting that I haven't actually compiled any of these examples - they might well not work at all.
Anyway, to get this fully working in python it should just be a case of doing similar for every structure, class, property & function that you want accessible from python - which is potentially quite a time consuming task!
If you want to see another example of this in action, I did this here to wrap up this class
Building & using the extension
Visual studio should take care of building the extension - then using it is just a case of taking the .DLL and renaming it to .pyd (you can get VS to do this for you, but I'll leave that up to you).
Then you just need to copy your python file to somewhere on your python path (site-packages for example), import it and use it!
import brisk
patternPoint = brisk.BriskPatternPoint()
....
Anyway, I have spent a good hour or so writing this out - so I'm going to stop here. Apologies if I've left anything out or if anything isn't clear, but I'm doing this mostly from memory. Hopefully it's been of some help to you. If you need anything clarified please just leave a comment, or ask another question.
In case someone needs it, this what I have so far. Basically a BriskFeatureDetector that can be created in Python and then have detect called. Most of this is just confirming/copying what obmarg showed me, but I have added the details that get all the way to the pyd library.
The detect method is still incomplete for me though since it does not convert data types. Anyone who knows a good way to improve this, please do! I did find, for example, this library which seems to convert a numpy ndarray to a cv::Mat, but I don't have the time to figure out how to integrate it now. There are also other data types that need to be converted.
Install OpenCV 2.2
for the setup below, I installed to C:\opencv2.2
Something about the API or implementation has changed by version 2.4 that gave me problems (maybe the new Algorithm object?) so I stuck with 2.2 which BRISK was developed with.
Install Boost with Boost Python
for the setup below, I installed to C:\boost\boost_1_47
Create a Visual Studio 10 Project:
new project --> win32
for the setup below, I named it brisk
next --> DLL application type; empty project --> finished
at the top, change from Debug Win32 to Release Win32
Create main.cpp in Source Files
Do this before the project settings so the C++ options become available in the project settings
#include <boost/python.hpp>
#include <opencv2/opencv.hpp>
#include <brisk/brisk.h>
BOOST_PYTHON_MODULE(brisk)
{
using namespace boost::python;
//this long mess is the only way I could get the overloaded signatures to be accepted
void (cv::BriskFeatureDetector::*detect_1)(const cv::Mat&,
std::vector<cv::KeyPoint, std::allocator<cv::KeyPoint>>&,
const cv::Mat&) const
= &cv::BriskFeatureDetector::detect;
void (cv::BriskFeatureDetector::*detect_vector)(const std::vector<cv::Mat, std::allocator<cv::Mat>>&,
std::vector< std::vector< cv::KeyPoint, std::allocator<cv::KeyPoint>>, std::allocator< std::vector<cv::KeyPoint, std::allocator<cv::KeyPoint>>>>&,
const std::vector<cv::Mat, std::allocator<cv::Mat>>&) const
= &cv::BriskFeatureDetector::detect;
class_< cv::BriskFeatureDetector >( "BriskFeatureDetector", init<int, int>())
.def( "detect", detect_1)
;
}
Project Settings (right-click on the project --> properties):
Includes / Headers
Configuration Properties --> C/C++ --> General
add to Additional Include Directories (adjust to your own python / brisk / etc. base paths):
C:\opencv2.2\include;
C:\boost\boost_1_47;
C:\brisk\include;C:\brisk\thirdparty\agast\include;
C:\python27\include;
Libraries (linker)
Configuration Properties --> Linker --> General
add to Additional Library Directories (adjust to your own python / brisk / etc. base paths):
C:\opencv2.2\lib;
C:\boost\boost_1_47\lib;
C:\brisk\win32\lib;
C:\python27\Libs;
Configuration Properties --> Linker --> Input
add to Additional Dependencies (adjust to your own python / brisk / etc. base paths):
opencv_imgproc220.lib;opencv_core220.lib;opencv_features2d220.lib;
agast_static.lib; brisk_static.lib;
python27.lib;
.pyd output instead of .dll
Configuration Properties --> General
change Target Extension to .pyd
Build and rename if necessary
Right-click on the solution and build/rebuild
you may need to rename the output from "Brisk.pyd" to "brisk.pyd" or else python will give you errors about not being able to load the DLL
Make brisk.pyd available to python by putting it in site packages or by putting a .pth file that links to its path
Update Path environment variable
In windows settings, make sure the following are included in your path (again, adjust to your paths):
`C:\boost\boost_1_47\lib;C:\brisk\win32\bin`