Python – K length decimal Places

In Python, controlling the number of decimal places in your numeric values is essential for presenting results accurately and efficiently. This article explores techniques to manage K-length decimal places in Python. Given a Decimal Number, extend its digits to K length.

Input: num = 76.8, K = 5 
Output: 76.80000 
Explanation: Length of decimal places is 5. 
Input: num = 76.8, K = 6 
Output: 76.800000 
Explanation: Length of decimal places is 6.

Find K-length decimal Places using Format() 

Python's format() function allows specifying decimal places for numeric values. This is the way in which this task can be done. In this, we harness multiple format compatibilities to perform the task of getting the appropriate length of decimal places.

Python3

num = 76.8

# printing original number
print("The original number is : " + str(num))

# initializing K
K = 7

# using format to solve this problem
res = "{{:.{}f}}".format(K).format(num)

print("The resultant number : " + str(res))

Output:

The original number is : 76.8
The resultant number : 76.8000000

Find K-length decimal Places using f-string

Python's f-stringallows specifying decimal places for numeric values. First Define a function format_decimal_places that takes a number num and an integer K as inputs. Inside the function, use an f-string to format the number with the specified number of decimal places K. And it will Return the formatted number.

Python3

def format_decimal_places(num, K):
    formatted_num = f"{num:.{K}f}"
    return formatted_num

num = 76.8
K = 5
output = format_decimal_places(num, K)
print(output)

Output:

76.80000

Find K-length decimal Places using str(),index() and len() methods

In Python you can find K-length decimal places in a floating-point number using a combination of string manipulation methods such as str(), index(), and len().

Python3

num = 76.8

# printing original number
print("The original number is : " + str(num))

# initializing K
K = 7
num = str(num)
x = num[num.index(".")+1:]
y = "0"*(K-len(x))
res = num+y

print("The resultant number : " + str(res))

Output:

The original number is : 76.8
The resultant number : 76.8000000

Find K-length decimal Places using Round() Function

Python's round() function to find K-length decimal places in a floating-point number involves rounding the number to K decimal places and then converting it back to a string to obtain the desired representation.

Python3

def find_k_decimal_places(num, k):
    rounded_num = round(num, k)
    rounded_str = str(rounded_num)
    decimal_index = rounded_str.index('.')
    return rounded_str[decimal_index + 1:]

# Example usage
value = 9.99999
k = 4
result = find_k_decimal_places(value, k)
print(result)

Output:

0

Find K-length decimal Places using the 'Decimal' class

• Define the function decimal_class_decimal(num, k).
• Convert the floating-point number num to a Decimal object using Decimal(str(num)).
• Use the quantize() method to round the Decimal number to k decimal places with ROUND_HALF_UP rounding mode: .quantize(Decimal(f"1e-{k}"), rounding=ROUND_HALF_UP).
• Return the quantized Decimal number.
• Set initial values for num and k: num = 76.8 and k = 5.
• Call the decimal_class_decimal function with the given values: result = decimal_class_decimal(num, k).
• Print the result: print(result).

Python3

from decimal import Decimal, ROUND_HALF_UP

def decimal_class_decimal(num, k):
    # Convert the floating-point number 'num' to a Decimal object
    decimal_num = Decimal(str(num))
    
    # Quantize the Decimal number to 'k' decimal places using ROUND_HALF_UP rounding mode
    decimal_num = decimal_num.quantize(Decimal(f"1e-{k}"), rounding=ROUND_HALF_UP)
    
    # Return the quantized Decimal number
    return decimal_num

# Example usage:
# Set the initial values for 'num' and 'k'
num = 76.8
k = 5

# Call the 'decimal_class_decimal' function with the given values
result = decimal_class_decimal(num, k)

# Print the result
print(result)

Output

76.80000

Time Complexity: O(d + k)

Auxiliary Space Complexity: O(d + k)