danijar/layered

import os
import errno
import functools
import itertools


def repeated(iterable, times):
    for _ in range(times):
        yield from iterable


def batched(iterable, size):
    batch = []
    for element in iterable:
        batch.append(element)
        if len(batch) == size:
            yield batch
            batch = []
    if batch:
        yield batch


def averaged(callable_, batch):
    overall = None
    for element in batch:
        current = callable_(element)
        overall = overall + current if overall else current
    return overall / len(batch)


def listify(fn=None, wrapper=list):
    """
    From http://stackoverflow.com/a/12377059/1079110
    """
    def listify_return(fn):
        @functools.wraps(fn)
        def listify_helper(*args, **kw):
            return wrapper(fn(*args, **kw))
        return listify_helper

    if fn is None:
        return listify_return
    return listify_return(fn)


def ensure_folder(path):
    try:
        os.makedirs(path)
    except OSError as e:
        if e.errno == errno.EEXIST:
            return
        raise


def hstack_lines(blocks, sep=' '):
    blocks = [x.split('\n') for x in blocks]
    height = max(len(block) for block in blocks)
    widths = [max(len(line) for line in block) for block in blocks]
    output = ''
    for y in range(height):
        for x, w in enumerate(widths):
            cell = blocks[x][y] if y < len(blocks[x]) else ''
            output += cell.rjust(w, ' ') + sep
        output += '\n'
    return output


def pairwise(iterable):
    a, b = itertools.tee(iterable)
    next(b, None)
    return zip(a, b)