Simple library function to find if a given sequence appears in the array somewhere.

README.md

Description

Simple library function in Python to find if a given sequence appears in the array somewhere.

How the code was developed

Initially the test function test_one_element_sequence() was added. Then enough code was written to make this test function pass. This TDD process was followed until sufficient test cases were written and code modified to make all tests pass.

##Usage The source code should be in the following directory structure:

• Root folder
  • array_util
    • __init__.py (empty file)
    • array_util.py
  • tests
    • test_sequence_in_array.py

From the command line, cd to the tests folder and run

   python test_sequence_in_array.py

##Development environment The code was written on a Windows 7 machine with Python 3.5.1.

array_util.py

class ArrayUtil:

    def is_sequence_present(self, input_array, sequence_to_check):
        len_sequence = len(sequence_to_check)
        if len_sequence == 0:
            return False

        for i in range((len(input_array) - len_sequence)+1):
            if self.__get_no_of_sequence_elements_present(
                    input_array, i, sequence_to_check) == len(sequence_to_check):
                return True

        return False

    def __get_no_of_sequence_elements_present(self, input_array,
                                                  index_to_start,
                                                  sequence_to_check):
        len_sequence = len(sequence_to_check)
        no_of_elements_present = 0

        for array_idx, seq_idx in zip(range(index_to_start, index_to_start+len_sequence),
                                      range(len_sequence)):
                if input_array[array_idx] == sequence_to_check[seq_idx]:
                    no_of_elements_present = no_of_elements_present + 1
                    continue
                else:
                    break

        return no_of_elements_present

test_sequence_in_array.py

#!/usr/bin/env python3

import sys
import unittest

sys.path.append('..')

from array_util import array_util


class FindSequenceTest(unittest.TestCase):

    def test_one_element_sequence(self):
        self.assertTrue(array_util.ArrayUtil().is_sequence_present(
            [3, 8, 1, 4], [1]))

    def test_no_sequence_present(self):
        self.assertFalse(array_util.ArrayUtil().is_sequence_present(
            [3, 8, 1, 4], [1, 3, 4]))

    def test_3_element_sequence(self):
        self.assertTrue(array_util.ArrayUtil().is_sequence_present(
            [3, 8, 99, 1, 3, 4, 6, 7], [1, 3, 4]))

    def test_sequence_at_end(self):
        self.assertTrue(array_util.ArrayUtil().is_sequence_present(
            [3, 8, 99, 1, 3, 4, 6, 7], [6, 7]))

    def test_empty_sequence(self):
        self.assertFalse(array_util.ArrayUtil().is_sequence_present(
            [1, 2, 3], []))


if __name__ == '__main__':
    unittest.main()