Python (1)¶
Examples from this notebook.
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using PyCall
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# Get Python version information
PyCall.pyversion
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math = pyimport("math")
math.sin(math.pi / 4) # returns ≈ 1/√2 = 0.70710678...
Python (2)¶
You can also write your own Python code as follows:
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x = [-0.6, -0.2, 0.2, 0.6]
y = [5., 3., 5., 8.]
py"""
import numpy as np
def corrcoef_numpy(xvals,yvals):
return np.corrcoef(xvals,yvals)[0][1]
"""
corrcoef_numpy = py"corrcoef_numpy"
println("correlation coefficient: $(corrcoef_numpy(x,y))")
Here is an example:
#include <stdio.h>
void say_y(int y) {
printf("Hello from C: got y = %d.\n", y);
}
Create a shared library. My command (on a MacBook Air M2):
gcc -shared -o mylib.dylib -fPIC mylib.c
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@ccall "./misc/mylib.dylib".say_y(5::Cint)::Cvoid
Hello from C: got y = 5.
hello.cpp
in directory hello
:
#include <string>
#include "jlcxx/jlcxx.hpp"
std::string greet() {
return "hello, world";
}
JLCXX_MODULE define_julia_module(jlcxx::Module& mod) {
mod.method("greet", &greet, "documentation for greet");
}
It is convenient to use cmake. Here is CMakeLists.txt
:
project(hello)
cmake_minimum_required(VERSION 3.5)
set(CMAKE_MACOSX_RPATH 1)
set(CMAKE_LIBRARY_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}/lib")
find_package(JlCxx)
get_target_property(JlCxx_location JlCxx::cxxwrap_julia LOCATION)
get_filename_component(JlCxx_location ${JlCxx_location} DIRECTORY)
set(CMAKE_INSTALL_RPATH "${CMAKE_INSTALL_PREFIX}/lib;${JlCxx_location}")
message(STATUS "Found JlCxx at ${JlCxx_location}")
add_library(hello SHARED hello.cpp)
target_link_libraries(hello JlCxx::cxxwrap_julia)
install(TARGETS
hello
LIBRARY DESTINATION lib
ARCHIVE DESTINATION lib
RUNTIME DESTINATION lib)
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module CppHello
using CxxWrap
@wrapmodule(() -> joinpath("./misc/build/lib","libhello"))
function __init__()
@initcxx
end
end
Main.CppHello
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CppHello.greet()
"hello, world"