Python: Determine the direction ('increasing' or 'decreasing') of monotonic sequence numbers

Last update on April 17 2025 13:09:33 (UTC/GMT +8 hours)

Determine Monotonic Direction

Monotonic sequences are sequences, which constantly increase or constantly decrease.
Write a Python program to determine the direction ('increasing' or 'decreasing') of monotonic sequence numbers.

Input:
[1, 2, 3, 4, 5, 6]
Output:
Increasing.

Input:
[6, 5, 4, 3, 2, 1]
Output:
Decreasing.

Input:
[19, 19, 5, 5, 5, 5, 5]
Output:
Not a monotonic sequence!

Visual Presentation:

Sample Solution:

Python Code:

# License: https://bit.ly/3oLErEI

# Define a function named 'test' that takes a list of numbers 'nums' as input
def test(nums):
    # Check if all elements in the list 'nums' are in increasing order
    if all(nums[i] < nums[i + 1] for i in range(len(nums) - 1)):
        return "Increasing."
    # Check if all elements in the list 'nums' are in decreasing order
    elif all(nums[i + 1] < nums[i] for i in range(len(nums) - 1)):
        return "Decreasing."
    else:
        return "Not a monotonic sequence!"

# Assign a specific list of numbers 'nums' to the variable
nums = [1, 2, 3, 4, 5, 6]

# Print the original list of numbers 'nums'
print("Original list:")
print(nums)

# Print a message indicating the operation to be performed
print("Check the direction ('increasing' or 'decreasing') of the said list:")

# Print the result of the test function applied to the 'nums' list
print(test(nums))

# Assign a different list of numbers 'nums' to the variable
nums = [6, 5, 4, 3, 2, 1]

# Print the original list of numbers 'nums'
print("\nOriginal list:")
print(nums)

# Print a message indicating the operation to be performed
print("Check the direction ('increasing' or 'decreasing') of the said list:")

# Print the result of the test function applied to the updated 'nums' list
print(test(nums))

# Assign another different list of numbers 'nums' to the variable
nums = [19, 19, 5, 5, 5, 5, 5]

# Print the original list of numbers 'nums'
print("\nOriginal list:")
print(nums)

# Print a message indicating the operation to be performed
print("Check the direction ('increasing' or 'decreasing') of the said list:")

# Print the result of the test function applied to the updated 'nums' list
print(test(nums))

Sample Output:

Original list:
[1, 2, 3, 4, 5, 6]
Check the direction ('increasing' or 'decreasing') of the said list:
Increasing.

Original list:
[6, 5, 4, 3, 2, 1]
Check the direction ('increasing' or 'decreasing') of the said list:
Decreasing.

Original list:
[19, 19, 5, 5, 5, 5, 5]
Check the direction ('increasing' or 'decreasing') of the said list:
Not a monotonic sequence!

Flowchart:

For more Practice: Solve these Related Problems:

• Write a Python program to determine if a sequence of numbers is strictly increasing, strictly decreasing, or neither.
• Write a Python program to compare each element with the previous one and output 'Increasing', 'Decreasing', or 'Not a monotonic sequence'.
• Write a Python program to implement a function that checks monotonicity by using pairwise comparisons.
• Write a Python program to verify the direction of a sequence using the all() function with a generator expression.

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