for循环中判断当前元素是否是最后一个元素

lookahead_iterable.py

def lookahead(iterable):
    """Pass through all values from the given iterable, augmented by the
    information if there are more values to come after the current one
    (True), or if it is the last value (False).
    """
    # Get an iterator and pull the first value.
    it = iter(iterable)
    last = next(it)
    # Run the iterator to exhaustion (starting from the second value).
    for val in it:
        # Report the *previous* value (more to come).
        yield last, True
        last = val
    # Report the last value.
    yield last, False

for i, has_more in lookahead(range(3)):
    print(i, has_more)
# 0 True
# 1 True
# 2 False

# 添加一个序号, 方便拿到index
def lookahead(iterable):
    """Pass through all values from the given iterable, augmented by the
    information if there are more values to come after the current one
    (True), or if it is the last value (False).
    """
    count = 0
    # Get an iterator and pull the first value.
    it = iter(iterable)
    last = next(it)
    # Run the iterator to exhaustion (starting from the second value).
    for val in it:
        # Report the *previous* value (more to come).
        count  +=1
        yield count,last, True
        last = val
    # Report the last value.
    count  +=1
    yield count,last, False

for i, line, has_more in lookahead(range(3)):
    print(i, line, has_more)