Python program to find the smallest number in a file

Given a  text file, write a Python program to find the smallest number in the given text file.

Examples:

Input: gfg.txt
Output: 9

Explanation: 
Contents of gfg.txt: I live at 624 Hyderabad.
My mobile number is 52367. My favourite number is 9.
Numbers present in the text file are 9,624,52367
Minimum number is 9.

Approach:

• Create a file object using the open function and pass the filename as parameter.
• Read the contents in the file using readlines() function.
• For each line in the file, Using regex find all integers present in that line.
• Create a result variable to store the final answer.
• If a number in a line is less than the current result then update the result.
• Close the file object.
• Return the result.

Below is the implementation of the above approach.

Python3

# Function to find smallest number in a text file.
import math
import re


def findMinimumElement(fileName):

    # Create a file object using open
    # function and pass filename as parameter.
    file = open(fileName, 'r')

    # Split into lines.
    lines_in_file = file.readlines()

    # Creating a result
    # variable to store final answer.
    result = math.inf
    for line in lines_in_file:

        # For each line in the file,
        # Using regex find all integers
        # present in that line.
        nums = list(map(int, re.findall('[0-9]+', line)))
        for i in nums:

            # If a number in a line is less
            # than the current result then
            # update the result.
            result = min(result, i)

    file.close()
    return result


# Creating sample text file for testing
with open("gfg.txt", "w") as file:
    g
    file.write(
        "I live at 624 Hyderabad. \
        My mobile number is 52367. \
        My favourite number is 9.")

print('Smallest number in the file is:',
      findMinimumElement('gfg.txt'))

Output:

Smallest number in the file is: 9

Complexity analysis:

Time complexity: O(n)
Auxiliary Space: O(n)

Method : Using sort() method

Python3

# Function to find smallest number in a text file.
import math
import re
def findMinimumElement(fileName):

    # Create a file object using open
    # function and pass filename as parameter.
    file = open(fileName, 'r')

    # Split into lines.
    lines_in_file = file.readlines()

    # Creating a result
    # variable to store final answer.
    result = math.inf
    for line in lines_in_file:

        # For each line in the file,
        # Using regex find all integers
        # present in that line.
        nums = list(map(int, re.findall('[0-9]+', line)))
        nums.sort()
        result=nums[0]
    file.close()
    return result


# Creating sample text file for testing
with open("gfg.txt", "w") as file:
    file.write(
        "I live at 624 Hyderabad. \
        My mobile number is 52367. \
        My favourite number is 9.")

print('Smallest number in the file is:',findMinimumElement('gfg.txt'))

Output

Smallest number in the file is: 9

Complexity analysis:

N is the number of words.

Time complexity: O(n)
Auxiliary Space: O(n)