tcosmo / dichoseek

Testing membership in sorted binary files.

Dichoseek

Dichoseek tests the membership of a n-byte encoded integer in a sorted binary file consisting of a succession of n-byte integers.

The name comes from the fact that the algorithm is a dichotomy (binary search) using the file seek function.

Instal

pip install dichoseek

Basic usage

Assuming that you are looking for a 4-byte unsigned integer (you can change this assumption):

from dichoseek import dichoseek
elem = 124
is_elem_in_file = dichoseek("path/to/file", elem)

Or using a file object:

from dichoseek import dichoseek
elem = 124
with open("path/to/file", "rb") as f:
  is_elem_in_file = dichoseek(f, elem)

Other parameters

• block_size: number of bytes per integer. We assume that the size of the file is a multiple of this block_size. Default is 4.

• block_interpretation_function is the function that is used to transform bytes into int. Default is unsigned, big-endian parsing: lambda b: int.from_bytes(b, byteorder="big").