Update linear_search.py

[Ashley-J-George]

I've added a Python implementation of recursive search algorithm

Describe your change:

• Add an algorithm?
• Fix a bug or typo in an existing algorithm?
• Documentation change?

Checklist:

• I have read CONTRIBUTING.md.
• This pull request is all my own work -- I have not plagiarized.
• I know that pull requests will not be merged if they fail the automated tests.
• This PR only changes one algorithm file. To ease review, please open separate PRs for separate algorithms.
• All new Python files are placed inside an existing directory.
• All filenames are in all lowercase characters with no spaces or dashes.
• All functions and variable names follow Python naming conventions.
• All function parameters and return values are annotated with Python type hints.
• All functions have doctests that pass the automated testing.
• All new algorithms have a URL in its comments that points to Wikipedia or other similar explanation.
• If this pull request resolves one or more open issues then the commit message contains Fixes: #{$ISSUE_NO}.

[spamegg1]

@Ashley-J-George Hi there, Your first PR ever huh? Good luck!

It looks like you did not provide any doctests for rec_linear_search.
rec_linear_search still has the same doctests as linear_search.
Can you provide some different doctests that use rec_linear_search instead?

There is an issue when, for example, low or high are greater than len(sequence). It would give a list index out of bounds error. Maybe handle it with an exception?

Also, type hints for both linear_search and rec_linear_search would be appreciated. For example:

def rec_linear_search(sequence: list, low: int, high: int, target: float) -> int:

[TravisBuddy]

Hey @Ashley-J-George,
Something went wrong with the build.

TravisCI finished with status errored, which means the build failed because of something unrelated to the tests, such as a problem with a dependency or the build process itself.

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TravisBuddy Request Identifier: 340dc310-f65d-11ea-afed-a1bc0e34d213

[Ashley-J-George]

Hey @Ashley-J-George,
Something went wrong with the build.

TravisCI finished with status errored, which means the build failed because of something unrelated to the tests, such as a problem with a dependency or the build process itself.

@cclauss @spamegg1 How should I rectify this?

My actual code is

`
'''
This is pure Python implementation of recursive linear search algorithm
'''

def rec_linear_search(sequence: list, low: int, high: int, target: int) -> int:
'''
Pure implementation of recursive linear search algorithm in Python

:param sequence: An array of items
:param low: Lower bound of the array
:param high: Higher bound of the array
:param target: The element to be found
:return: Index of the key or -1 if key not found

Examples:
>>> rec_linear_search([0, 30, 500, 100, 700], 0, 4, 0)
The element 0 is present at index 0
>>> rec_linear_search([0, 30, 500, 100, 700], 0, 4, 700)
The element 700 is present at index 4
>>> rec_linear_search([0, 30, 500, 100, 700], 0, 4, 30)
The element 5 is present at index 1
>>> rec_linear_search([0, 30, 500, 100, 700], 0, 4, -6)
The element -6 is not present in the array
'''
if high < low:
    return -1
try:
    if sequence[low] == target:
        return low
    if sequence[high] == target:
        return high
    return rec_linear_search(sequence, low + 1, high - 1, target)
except IndexError:
    print('Invalid upper or lower bound!')

def main():
arr = list(map(int, input('Enter space separated values: ').split())) # Maps each input into an integer
key = int(input('Enter the value you want to search: '))
index = rec_linear_search(arr, 0, len(arr) - 1, key)

if index:
    print("The element", key, "is present at index", index)
else:
    print("The element", key, "is not present in the array")

if name == 'main':
print(rec_linear_search([0, 30, 500, 100, 700], 0, 8, 700))

`

[Ashley-J-George]

When the element is not found I have made the function return -1, and added a try except to handle the index error

…

On Mon, Sep 14, 2020 at 1:08 PM Christian Clauss ***@***.***> wrote: ***@***.**** commented on this pull request. ------------------------------ In searches/linear_search.py <#2422 (comment)>: > + + Examples: + >>> linear_search([0, 5, 7, 10, 15], 0) + 0 + + >>> linear_search([0, 5, 7, 10, 15], 15) + 4 + + >>> linear_search([0, 5, 7, 10, 15], 5) + 1 + + >>> linear_search([0, 5, 7, 10, 15], 6) + + ''' + if high < low: + return None We promised on line 41 that this function would return an it but now we are returning an non-int. We have two choices: 1. Return -1 as a signal that the element is not in the list --or-- 2. Raise an error. This is like str.find() <https://docs.python.org/3/library/stdtypes.html#str.find> vs. str.index <https://docs.python.org/3/library/stdtypes.html#str.index>. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#2422 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AJUYHLIMUQZOAKBQSFPDUITSFXB6PANCNFSM4RK2FGDQ> .

[TravisBuddy]

Hey @Ashley-J-George,
Something went wrong with the build.

TravisCI finished with status errored, which means the build failed because of something unrelated to the tests, such as a problem with a dependency or the build process itself.

View build log

TravisBuddy Request Identifier: 156ed5e0-f660-11ea-afed-a1bc0e34d213

[spamegg1]

@Ashley-J-George Build log says

3 W293 blank line contains whitespace

Very easy to fix! Check out CONTRIBUTING.md about running black on your code.
You are almost there my friend! Good luck 👍

[cclauss]

Nice work!!

[Ashley-J-George]

Thank You!