Linear Search in Python

Welcome to the Linear Search in Python page! Here, you'll find the source code for this program as well as a description of how the program works.

Current Solution

import sys


def sysarg_to_list(string: str):
    return [int(x.strip(" "), 10) for x in string.split(',')]


def linear_search(array: list, key: int) -> bool:
    for item in array:
        if item == key:
            return True
    return False


if len(sys.argv) != 3 or not sys.argv[1]:
    print('Usage: please provide a list of integers ("1, 4, 5, 11, 12") and the integer to find ("11")')
else:
    key = int(sys.argv[2])
    array = sysarg_to_list(sys.argv[1])
    print(linear_search(array, key))

Linear Search in Python was written by:

• frankhart2017
• Jeremy Grifski
• rzuckerm
• Siddhartha Dhar Choudhury

This article was written by:

• frankhart2017
• Jeremy Grifski
• rzuckerm

If you see anything you'd like to change or update, please consider contributing.

How to Implement the Solution

Let's break up the code into parts to get a deeper understanding of the entire code.

Convert String to List of Integers

def sysarg_to_list(string: str):
    return [int(x.strip(" "), 10) for x in string.split(',')]

This function takes a string like "2, 1, 10, 5, 3", and turns into a list of numbers. It does this using a list comprehension, first we need to convert our string into a list string.split(',') which is a list of strings split by comma (,). So our original input string becomes ["2", " 1", " 10", " 5", " 3"]. Then for each element in the list for x in ... , we do something to it.

In this example we convert it into a decimal integer, int(x.strip(" "), 10). Then x.strip(" "), removes any whitespace so " 1" becomes "1". Then int("1", 10) converts the string "1" into a decimal number in this case 1. This is done for every item in the list so our original input of "2, 1, 10, 5, 3" becomes [2, 1, 10, 5, 3].

Linear Search

def linear_search(array: list, key: int) -> bool:
    for item in array:
        if item == key:
            return True
    return False

This function loops through each element in array comparing current value (item) to the desired value (key). When a match is found, True is returned. When all values have been compared, and no match is found, False is returned.

Get User Input and Process It

if len(sys.argv) != 3 or not sys.argv[1]:
    print('Usage: please provide a list of integers ("1, 4, 5, 11, 12") and the integer to find ("11")')
else:
    key = int(sys.argv[2])
    array = sysarg_to_list(sys.argv[1])
    print(linear_search(array, key))

The first command-line argument is a string containing a comma-separated list of integers, and the second command-line argument is the value to find. If the number of arguments is not correct, or the first argument is empty, a user statement is displayed. Otherwise, the following is done:

• Convert the value to find (sys.argv[2]) to an integer
• Call sysarg_to_list to convert the string to a list of integers
• Call linear_search to search for the value in the list
• Call print to display the result of the search

How to Run the Solution

If we want to run this program, we should probably download a copy of Linear Search in Python. After that, we should make sure we have the latest Python interpreter. From there, we can run the following command in the terminal:

python linear-search.py "3, 2, 6, 1, 7" "2"

Alternatively, we can copy the solution into an online Python interpreter and hit run.