You can use itertools.zip_longest: import itertools np.array(list(itertools.zip_longest(*v, fillvalue=0))).T Out: array([[1, 0], [1, 2]]) Note: For Python 2, it is itertools.izip_longest.
MSVC is not a C99 compiler, and does not support variable length arrays. At https://learn.microsoft.com/en-us/cpp/c-language/ansi-conformance MSVC is documented as conforming to C90.
Here’s the allocation code (x86 – the x64 code is similar) for the following example line taken from some GCC docs for VLA support: char str[strlen (s1) + strlen (s2) + 1]; where the calculation for strlen (s1) + strlen (s2) + 1 is in eax (GCC MinGW 4.8.1 – no optimizations): mov edx, eax … Read more
That leeway wording doesn’t mean that any and everything in C99 is in C++11. What you quoted is just introductory text.
Create a large buffer (MB+) in thread-local storage. (Actual memory on heap, management in TLS). Allow clients to request memory from it in FILO manner (stack-like). (this mimics how it works in C VLAs; and it is efficient, as each request/return is just an integer addition/subtraction). Get your VLA storage from it. Wrap it pretty, … Read more
For reasons that are not entirely clear to me, almost every time the topic of C99 VLA pops up in a discussion, people start talking predominantly about the possibility of declaring run-time-sized arrays as local objects (i.e. creating them “on the stack”). This is rather surprising and misleading, since this facet of VLA functionality – … Read more
No they’re not absolutely the same. While both let you store the same number and type of objects, keep in mind that: You can free() a malloced array, but you can’t free() a variable length array (although it goes out of scope and ceases to exist once the enclosing block is left). In technical jargon, … Read more
Yes, alloca is functionally equivalent to a local variable length array, i.e. this: int arr[n]; and this: int *arr = alloca(n * sizeof(int)); both allocate space for n elements of type int on the stack. The only differences between arr in each case is that 1) one is an actual array and the other is … Read more
VLA does have some overhead (compared to “ordinary” named compile-time-sized array). Firstly, it has run-time length and yet the language provides you with means to obtain the actual size of the array at run-time (using sizeof). This immediately means that the actual size of the array has to be stored somewhere. This results in some … Read more
This is not a “static memory allocation”. Your array k is a Variable Length Array (VLA), which means that memory for this array is allocated at run time. The size will be determined by the run-time value of n. The language specification does not dictate any specific allocation mechanism, but in a typical implementation your … Read more