Binary search on python sorted sequences

pip install binary-search==0.3.0


Binary Search in Python

Binary search on already sorted sequences (list, tuple) to get the first element >= or > a value (similar to C++'s std::lower_bound and std::upper_bound).

Requires python >=3.5 for the typing module and >= 3.4 for the enum module, but you can easily extract the search function from binary_search/ if you need it for a lower version.


  1. pip install binary-search


See for more sample usage.

import binary_search as bs

sorted_sequence = (2, 5, 7, 9)
a =, 5)
print(a) # 1 - the index of the first element >= 5

b =, 6)
print(b) # 2 - the index of the first element >= 6 (element 2 with value 7)

You can also use a custom key in the same way as sorted

import binary_search as bs
import random

# sequence of 10 random pairs of integers
sequence = [(random.randint(), random.randint()) for _ in range(10)]
# sort and search just using the first integer
key = lambda pair: pair[0]

sorted_sequence = sorted(sequence, key=key), [5, None], key=key)

Development and testing

  1. Fork the repository
  2. Clone your fork
  3. Install it in editable mode pip install -e .
  4. Make any changes and add new tests to
  5. Run pytest python -m pytest
  6. Commit and push to your fork
  7. Make pull request (merge your fork back to main repo)