>>> list(itertools.product(*arrays)) [(-1, -2, -3), (-1, -2, 3), (-1, 2, -3), (-1, 2, 3), (1, -2, -3), (1, -2, 3), (1, 2, -3), (1, 2, 3)] This will feed all the pairs as separate arguments to product, which will then give you the cartesian product of them. The reason your version isn’t working is that … Read more
Just because you call it clusterList doesn’t make it a list! It’s basically a lazy iterator, returning each item as it’s needed. You can convert it to a list like this, though: clusterList = list(clusterList) Or do that and get its length in one step: length = len(list(clusterList)) If you don’t want to take up … Read more
islice() can be used to get the next n items of an iterator. Thus, list(islice(f, n)) will return a list of the next n lines of the file f. Using this inside a loop will give you the file in chunks of n lines. At the end of the file, the list might be shorter, … Read more
Right out of the box, zip() is hardwired to dispose of the unmatched item. So, you need a way to remember values before they get consumed. The itertool called tee() was designed for this purpose. You can use it to create a “shadow” of the first input iterator. If the second iterator terminates, you can … Read more
In Python 3 the built-in zip does the same job as itertools.izip in 2.X(returns an iterator instead of a list). The zip implementation is almost completely copy-pasted from the old izip, just with a few names changed and pickle support added. Here is a benchmark between zip in Python 2 and 3 and izip in … Read more
The first takes 0 or more arguments, each an iterable, the second one takes one argument which is expected to produce the iterables: from itertools import chain chain(list1, list2, list3) iterables = [list1, list2, list3] chain.from_iterable(iterables) but iterables can be any iterator that yields the iterables: def gen_iterables(): for i in range(10): yield range(i) itertools.chain.from_iterable(gen_iterables()) … Read more
zip computes all the list at once, izip computes the elements only when requested. One important difference is that ‘zip’ returns an actual list, ‘izip’ returns an ‘izip object’, which is not a list and does not support list-specific features (such as indexing): >>> l1 = [1, 2, 3, 4, 5, 6] >>> l2 = … Read more
class unique_element: def __init__(self,value,occurrences): self.value = value self.occurrences = occurrences def perm_unique(elements): eset=set(elements) listunique = [unique_element(i,elements.count(i)) for i in eset] u=len(elements) return perm_unique_helper(listunique,[0]*u,u-1) def perm_unique_helper(listunique,result_list,d): if d < 0: yield tuple(result_list) else: for i in listunique: if i.occurrences > 0: result_list[d]=i.value i.occurrences-=1 for g in perm_unique_helper(listunique,result_list,d-1): yield g i.occurrences+=1 a = list(perm_unique([1,1,2])) print(a) result: [(2, … Read more
Disclaimer: Yes, I know that this is not Python code. It just popped into my mind and I simply had to write it down. The simplest way is the use of shell expansion: $ echo MPP6R-09RXG-2H{8,B}MT-{B,8}K{H,N}M9-V{6,G}C8R MPP6R-09RXG-2H8MT-BKHM9-V6C8R MPP6R-09RXG-2H8MT-BKHM9-VGC8R MPP6R-09RXG-2H8MT-BKNM9-V6C8R MPP6R-09RXG-2H8MT-BKNM9-VGC8R MPP6R-09RXG-2H8MT-8KHM9-V6C8R MPP6R-09RXG-2H8MT-8KHM9-VGC8R MPP6R-09RXG-2H8MT-8KNM9-V6C8R MPP6R-09RXG-2H8MT-8KNM9-VGC8R MPP6R-09RXG-2HBMT-BKHM9-V6C8R MPP6R-09RXG-2HBMT-BKHM9-VGC8R MPP6R-09RXG-2HBMT-BKNM9-V6C8R MPP6R-09RXG-2HBMT-BKNM9-VGC8R MPP6R-09RXG-2HBMT-8KHM9-V6C8R MPP6R-09RXG-2HBMT-8KHM9-VGC8R MPP6R-09RXG-2HBMT-8KNM9-V6C8R MPP6R-09RXG-2HBMT-8KNM9-VGC8R