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zip() for parallel iteration

zip() lets you iterate over several iterables in parallel. It is a clean way to express "take one item from each sequence together" without indexing by hand.

What is zip()?​

names = ["Ada", "Grace", "Linus"]
scores = [95, 99, 88]

for name, score in zip(names, scores):
    print(name, score)

Output:

Ada 95
Grace 99
Linus 88

This is usually clearer than looping over indexes and then looking up values in each list.

Why it is useful​

zip() helps when:

  • two sequences belong together
  • parallel iteration is the real task
  • manual indexing would add noise

It also combines well with unpacking, which keeps the loop body simple.

One important detail​

zip() stops when the shortest iterable runs out.

That is often exactly what you want, but it can hide mismatched lengths if the data should always line up.

note

If equal lengths are required, it is worth validating that assumption instead of relying on zip() silently truncating.

Rules of thumb​

  • Use zip() when iterating over related sequences together.
  • Prefer it over manual index-based loops for parallel data.
  • Remember that it stops at the shortest iterable.
  • Validate lengths when truncation would be a bug.