This is, again, because Cython simply calls the C APIs in the Python runtime that create and manipulate those objects. Thus Python data structures behave much like Cython-optimized Python code generally: You sometimes get a boost, but only a little. For best results, use C variables and structures. The good news is Cython makes it easy to work with them. If you have a function in C labeled with the cdef keyword, with all of its variables and inline function calls to other things that are pure C, it will run as fast as C can go.
But if that function references any Python-native code, like a Python data structure or a call to an internal Python API, that call will be a performance bottleneck.
Fortunately, Cython provides a way to spot these bottlenecks: a source code report that shows at a glance which parts of your Cython app are pure C and which parts interact with Python. The better optimized the app, the less interaction there will be with Python. A source code report generated for a Cython application. A well-optimized Cython program will have as little yellow as possible. The expanded last line shows the C code underyling its corresponding Cython code.
Cython improves the use of C-based third-party number-crunching libraries like NumPy. But NumPy, in particular, works well with Cython. Cython has native support for specific constructions in NumPy and provides fast access to NumPy arrays. The cimport statement, for instance, allows Cython code to see C-level constructs in libraries at compile time for the fastest possible bindings. You get the best performance from any piece of code by profiling it and seeing firsthand where the bottlenecks are.
The less you shuttle back and forth between Python and Cython, the faster your app will run. Pass the entire collection to your Cython module and iterate there. We use Python because it provides programmer convenience and enables fast development. Sometimes that programmer productivity comes at the cost of performance. With Cython, just a little extra effort can give you the best of both worlds. Serdar Yegulalp is a senior writer at InfoWorld, focused on machine learning, containerization, devops, the Python ecosystem, and periodic reviews.
Find the factorial of a number. Print the Fibonacci sequence. Check leap year. Reference Materials Built-in Functions. List Methods. Dictionary Methods. String Methods. Start Learning Python. Explore Python Examples. Related Topics Python exec. Python Programming Built-in Functions. Python Input, Output and Import. Python compile The compile method returns a Python code object from the source normal string, a byte string, or an AST object.
If it wasn't read from a file, you can give a name yourself mode - Either exec or eval or single. Severance is speaking very broadly about the process of executing Python. The Python bytecode interpreter does result in a stream of machine instructions, the instructions it executes as it is interpreting the bytecode.
They are not stored anywhere before execution though. Bartek phrases the question right. An online real-time compiler is essentially an interpreter.
Of course, everything is ultimately converted into executable code for the instruction set that the platform support. Ned is absolutely right that compiled vs interpretation is an implementation issue and not a language issue. But some of us still care to know a language is natively compiled one time or compiled in real-time every time the code runs.
This is an awesome article! So much confusion out there.. Still some nagging stupid questions arise: Is Python-bytecode same as Java-bytecode? Not sure why one would do that but hey just asking?
Ned Batchelder AM on 3 Nov Taneli: Python bytecode and Java bytecode are different. Python bytecode can even change between versions 3. Gee Dee AM on 26 Nov Other one is: can it change operation with self modification of source code, yes?
Ned Batchelder PM on 26 Nov Gee Dee: your definition is definitely simple. So Java is an interpreted language? And the component of Python that converts source code into bytecode, what should we call that?
Whomper PM on 21 Feb Hi Ned, thanks for that! Brilliant as ever! It's important to know, that Python Source Code is compiled to Byte Code in a first step, just to understand the difference between Syntax Errors which appear in the compilation step and cxceptions, which appear at runtime.
I try to teach my students pretty early in the courses. Mark L AM on 7 Nov Wollo PM on 10 Nov Add a comment: Name:. Email: Ignore this:. Leave this empty:. Web site:. Name is required. Either email or web are required. Email won't be displayed and I won't spam you. Your web site won't be indexed by search engines.
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