I am trying to load a dynamic library <libname>.so which is present in current directory as well as in /use/lib, /lib, /lib32. but program is not able to find it to any of these path.
I am running a pascal program and it has this method
LibHandle := LoadLibrary( PAnsiChar(Trim('./libtrdp.so')) );
it fails and gives error.
"This binary has no dynamic library support compiled in.
Recompile the application with a dynamic-library-driver in the program uses clause before other units using dynamic libraries.
Runtime error 235 at $0805F292"
if anyone is aware of this issue then please let me know as I have searched on the internet but could not find the answer.
Note: I am running this program on Linux machine.
Add unit dynlibs to the uses clause.
On Linux, loadlibrary is an empty stub that gets filled when you add dynlibs. This is done to keep the base runtime libc+dl free.
This is the scenario:
I am using Python 3 (3.6 through 3.8 on Windows 10, using Pipenv and vanilla Python) to create an SQLite file with Spatial support and several triggers based on Spatial Indices.
Creating the database and adding records works just fine after loading Spatialite
conn.enable_load_extension(True)
conn.load_extension("mod_spatialite")
However, adding spatial links with code such as below
SELECT CreateSpatialIndex( 'nodes' , 'geometry' );"""
returns the following error
updateTableTriggers: "no such module: rtree"
I tried compiling the rtree extension following some recommendation from
Compiling SQLite RTREE in MSVC?
and using VS 2016 (16.4.2).
But I get all sorts of errors when trying to load that in SQL (Might not be compiling it properly, but I tried multiple things and nothing worked). My best attempt was a successful compilation using pretty much the instructions I referred to above, but when I attempted
p.conn.load_extension("libSqliteRtree.dll")
I got
sqlite3.OperationalError: The specified procedure could not be found.
I am really at loss here, as there seems to be very little discussion on this topic everywhere I looked. A few questions that come to mind are:
Are the specific compilation instructions/tricks/compiler versions that I should be using?
Is it even possible to compile and load rtree in Python 3 using the standard sqlite3 library?
Is this particular to Windows?
Are there alternative SQLite Python packages that could do the job (I didn't find any on PyPI)?
It is critical, however, that the solution works across different platforms.
I was just having the exact same problem, with Python 3.8 x64. I believe the problem was that the sqlite3.dll file inside my Python's installation DLLs folder had been compiled without RTREE enabled (https://sqlite.org/rtree.html).
To resolve this I visited the SQLite website, downloaded the .zip with the latest sqlite3.dll for Windows x64 (hoping RTREE would be enabled on that version, because I tried compiling it on my own and it didn't work), and swapped the old DLL in the DLLs folder with the newly downloaded DLL from the website. The RTREE error was gone! Detailed steps below:
Access https://sqlite.org/download.html and choose the "Precompiled Binaries for Windows" of your system. Mine was x64 because I was running Python x64. Download the .zip and unzip it.
Find your Python's installation folder (the folder which contains the python.exe you're running), and open the DLLs folder. You'll see there is a file there called sqlite3.dll. That's the one that comes with the Python installation.
Copy the sqlite3.dll from the unzipped folder in step 1 and paste into the DLLs folder, click Yes to substitute the file in the DLLs folder for the new one. That should solve the problem.
I'm trying out Freeling's API for python. The installation and test were ok, they provide a sample.py file that works perfectly (I've played around a little bit with it and it works).
So I was trying to use it on some other python code I have, in a different folder (I'm kind of guessing this is a path issue), but whenever I import freeling (like it shows on the sample.py):
import freeling
FREELINGDIR = "/usr/local";
DATA = FREELINGDIR+"/share/freeling/";
LANG="es";
freeling.util_init_locale("default");
I get this error:
ModuleNotFoundError: No module named 'freeling'.
The sample.py is located on the ~/Freeling-4.0/APIs/Python/ folder, while my other file is located in ~/project/, I dont know if that can be an issue.
Thank you!
A simple solution is to have a copy of freeling.py in the same directory as your code, since python will look there.
A better solution is to either paste it in one of the locations where it usually checks (like the lib folder in its install directory), or to tell it that the path where your file is should be scanned for a module.
You can check out this question to see how it can be done on Windows. You are basically just setting the PYTHONPATH environment variable, and there will only be minor differences in how to do so for other OSes. This page gives instructions that should work on Linux systems.
I like this answer since it adds the path at runtime in the script itself, doesn't make persistent changes, and is largely independent of the underlying OS (apart from the fact that you need to use the appropriate module path of course).
You need to set PYTHONPATH so python can find the modules if they are not in the same folder.
What is the best way to call java from python?
(jython and RPC are not an option for me).
I've heard of JCC: http://pypi.python.org/pypi/JCC/1.9
a C++ code generator for calling Java from C++/Python
But this requires compiling every possible call; I would prefer another solution.
I've hear about JPype: http://jpype.sourceforge.net/
tutorial: http://www.slideshare.net/onyame/mixing-python-and-java
import jpype
jpype.startJVM(path to jvm.dll, "-ea")
javaPackage = jpype.JPackage("JavaPackageName")
javaClass = javaPackage.JavaClassName
javaObject = javaClass()
javaObject.JavaMethodName()
jpype.shutdownJVM()
This looks like what I need.
However, the last release is from Jan 2009 and I see people failing to compile JPype.
Is JPype a dead project?
Are there any other alternatives?
You could also use Py4J. There is an example on the frontpage and lots of documentation, but essentially, you just call Java methods from your python code as if they were python methods:
from py4j.java_gateway import JavaGateway
gateway = JavaGateway() # connect to the JVM
java_object = gateway.jvm.mypackage.MyClass() # invoke constructor
other_object = java_object.doThat()
other_object.doThis(1,'abc')
gateway.jvm.java.lang.System.out.println('Hello World!') # call a static method
As opposed to Jython, one part of Py4J runs in the Python VM so it is always "up to date" with the latest version of Python and you can use libraries that do not run well on Jython (e.g., lxml). The other part runs in the Java VM you want to call.
The communication is done through sockets instead of JNI and Py4J has its own protocol (to optimize certain cases, to manage memory, etc.)
Disclaimer: I am the author of Py4J
Here is my summary of this problem: 5 Ways of Calling Java from Python
http://baojie.org/blog/2014/06/16/call-java-from-python/ (cached)
Short answer: Jpype works pretty well and is proven in many projects (such as python-boilerpipe), but Pyjnius is faster and simpler than JPype
I have tried Pyjnius/Jnius, JCC, javabridge, Jpype and Py4j.
Py4j is a bit hard to use, as you need to start a gateway, adding another layer of fragility.
Pyjnius docs and Github.
From the github page:
A Python module to access Java classes as Python classes using JNI.
PyJNIus is a "Work In Progress".
Quick overview
>>> from jnius import autoclass
>>> autoclass('java.lang.System').out.println('Hello world')
Hello world
>>> Stack = autoclass('java.util.Stack')
>>> stack = Stack()
>>> stack.push('hello')
>>> stack.push('world')
>>> print stack.pop()
world
>>> print stack.pop()
hello
If you're in Python 3, there's a fork of JPype called JPype1-py3
pip install JPype1-py3
This works for me on OSX / Python 3.4.3. (You may need to export JAVA_HOME=/Library/Java/JavaVirtualMachines/your-java-version)
from jpype import *
startJVM(getDefaultJVMPath(), "-ea")
java.lang.System.out.println("hello world")
shutdownJVM()
I'm on OSX 10.10.2, and succeeded in using JPype.
Ran into installation problems with Jnius (others have too), Javabridge installed but gave mysterious errors when I tried to use it, PyJ4 has this inconvenience of having to start a Gateway server in Java first, JCC wouldn't install. Finally, JPype ended up working. There's a maintained fork of JPype on Github. It has the major advantages that (a) it installs properly and (b) it can very efficiently convert java arrays to numpy array (np_arr = java_arr[:])
The installation process was:
git clone https://github.com/originell/jpype.git
cd jpype
python setup.py install
And you should be able to import jpype
The following demo worked:
import jpype as jp
jp.startJVM(jp.getDefaultJVMPath(), "-ea")
jp.java.lang.System.out.println("hello world")
jp.shutdownJVM()
When I tried calling my own java code, I had to first compile (javac ./blah/HelloWorldJPype.java), and I had to change the JVM path from the default (otherwise you'll get inexplicable "class not found" errors). For me, this meant changing the startJVM command to:
jp.startJVM('/Library/Java/JavaVirtualMachines/jdk1.7.0_79.jdk/Contents/MacOS/libjli.dylib', "-ea")
c = jp.JClass('blah.HelloWorldJPype')
# Where my java class file is in ./blah/HelloWorldJPype.class
...
I've been integrating a lot of stuff into Python lately, including Java. The most robust method I've found is to use IKVM and a C# wrapper.
IKVM has a neat little application that allows you to take any Java JAR, and convert it directly to .Net DLL. It simply translates the JVM bytecode to CLR bytecode. See http://sourceforge.net/p/ikvm/wiki/Ikvmc/ for details.
The converted library behaves just like a native C# library, and you can use it without needing the JVM. You can then create a C# DLL wrapper project, and add a reference to the converted DLL.
You can now create some wrapper stubs that call the methods that you want to expose, and mark those methods as DllEport. See https://stackoverflow.com/a/29854281/1977538 for details.
The wrapper DLL acts just like a native C library, with the exported methods looking just like exported C methods. You can connect to them using ctype as usual.
I've tried it with Python 2.7, but it should work with 3.0 as well. Works on Windows and the Linuxes
If you happen to use C#, then this is probably the best approach to try when integrating almost anything into python.
I'm just beginning to use JPype 0.5.4.2 (july 2011) and it looks like it's working nicely...
I'm on Xubuntu 10.04
I'm assuming that if you can get from C++ to Java then you are all set. I've seen a product of the kind you mention work well. As it happens the one we used was CodeMesh. I'm not specifically endorsing this vendor, or making any statement about their product's relative quality, but I have seen it work in quite a high volume scenario.
I would say generally that if at all possible I would recommend keeping away from direct integration via JNI if you can. Some simple REST service approach, or queue-based architecture will tend to be simpler to develop and diagnose. You can get quite decent perfomance if you use such decoupled technologies carefully.
Through my own experience trying to run some java code from within python in a manner similar to how python code runs within java code in python, I was unable to find a straightforward methodology.
My solution to my problem was by running this java code as BeanShell scripts by calling the BeanShell interpreter as a shell command from within my python code after editing the java code in a temporary file with the appropriate packages and variables.
If what I am talking about is helpful in any manner, I am glad to help you share more details of my solutions.
I'm attempting to package Mnemosyne, an application that uses PyQt, on Mac OS Lion via Py2app.
I'm getting several errors like the following:
objc[2826]: Class QCocoaView is implemented in both
/Volumes/Bullfrog/patrick/m2/./dist/Mnemosyne.app/Contents/MacOS/../Frameworks/libQtGui.4.dylib
and /opt/local/lib/libQtGui.4.dylib. One of the two will be used.
Which one is undefined.
objc[2826]: Class QCocoaWindow is implemented in both
/Volumes/Bullfrog/patrick/m2/./dist/Mnemosyne.app/Contents/MacOS/../Frameworks/libQtGui.4.dylib
and /opt/local/lib/libQtGui.4.dylib. One of the two will be used.
Which one is undefined.
The first version of the class is the one used in Py2App and is the one that should be used (I am trying to make the app standalone). The second is the system Qt that I installed via MacPorts. What do I have to add to the application to make it use the bundled Qt and not the system Qt?
And also several statements like this:
On Mac OS X, you might be loading two sets of Qt binaries into the
same process. Check that all plugins are compiled against the right Qt
binaries. Export DYLD_PRINT_LIBRARIES=1 and check that only one set of
binaries are being loaded. QObject::moveToThread: Current thread
(0x10246c880) is not the object's thread (0x106985d00). Cannot move to
target thread (0x10246c880)
Honestly I don't really understand how to do what I need to do here just based on this error message (I'm not a coder; I'm just doing my best to package the software).
This article gives a solution: simply add a blank qt.conf file in the application's Content/Resources directory.