What is the best way to get the number of elements in a PyTables row iterator?

Question

My current approach is:

rowiter = atable.where(condition)
rowiter_length = max([i for i, row in enumerate(rowiter)])

Is there a way to get the length of rowiter without looping through the entire iterator?

Answer 1

Not sure if there's a more efficient way, but you should really just be using len(rowiter) instead of that list comp, for two reasons:

1. If the iterator object DOES have a more efficient way of calculating its length, it'll most likely have made it accessible via the __len__ special method, so you'll get the speedup if it's available.
2. enumerate starts at index 0, so your construct will return 1 less than the actual length of the iterator.