Generator that breaks a sequence up into a given size for batch processing items in the sequence

batch.py

def batches(sequence, batch_size):
    """Iterate over a sequence in batches
    
    Example:
    for batch in batches([1, 2, 3, 4, 5, 6, 7], 3):
        process(batch)
    """
    try:
        sequence_length
    except NameError:
        sequence_length = len(sequence)
    for start_index in range(0, sequence_length, batch_size):
        end_index = min(start_index + batch_size, sequence_length)
        yield sequence[start_index:end_index]

I've seen similar examples here and there that always seem to restrict the sequence length to a multiple of the batch size. Why? I have no idea.

This behaves more sensibly: the last batch will contain however many items are remaining even if it's less than the full batch size.