I have the following problem. Given a list of integers L, I need to generate all of the sublists L[k:] for k in [0, len(L) – 1], without generating copies. How do I accomplish this in Python? With a buffer object somehow? Answer The short answer Slicing lists does not generate copies of the objects in t…
Why doesn’t list have safe “get” method like dictionary?
Why doesn’t list have a safe “get” method like dictionary? Answer Ultimately it probably doesn’t have a safe .get method because a dict is an associative collection (values are associated with names) where it is inefficient to check if a key is present (and return its value) without th…
Manually validate a django session id is currently authenticated
I need to have a function tell me if a Django session-id is currently authenticated or not. I understand this is already built into Django and I have that working just fine. But I have an external app that gets passed a session id, and when it passes the session-id string back to Django I need to validate tha…
Python interfacing with C library – How to have a null c pointer
I have the following old c code. Now, I need to use Python to call old c function. I have the following code. May I know what is the Python equivalent for c[2] = 0;? Answer None and 0 both work:
How to create a spinning command line cursor?
Is there a way to print a spinning cursor in a terminal using Python? Answer Something like this, assuming your terminal handles b
How can I write a `try`/`except` block that catches all exceptions?
How can I write a try/except block that catches all exceptions? Answer You can but you probably shouldn’t: However, this will also catch exceptions like KeyboardInterrupt and you usually don’t want that, do you? Unless you re-raise the exception right away – see the following example from th…
Implementing a function in Python vs C
Is there a difference (in terms of execution time) between implementing a function in Python and implementing it in C and then calling it from Python? If so, why? Answer Python (at least the “standard” CPython implementation) never actually compiles to native machine code; it compiles to bytecode …
tokenize in python3.x
I have following codes in python2.x: Now problem is that in python3.x second argument does not exist. I need to call the function operations.eat() before tokenize. How can we perform the above task in python3.x. One idea is to directly call the function tokenize.eat() before ‘tokenize’ statement(l…
What is the correct way to make my PyQt application quit when killed from the console (Ctrl-C)?
What is the correct way to make my PyQt application quit when killed from the console (Ctrl-C)? Currently (I have done nothing special to handle unix signals), my PyQt application ignores SIGINT (Ctrl+C). I want it to behave nicely and quit when it is killed. How should I do that? Answer 17.4. signal — Set ha…
Regular expression to return text between parenthesis
All I need is the contents inside the parenthesis. Answer If your problem is really just this simple, you don’t need regex: