Numpy round() Function

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The Numpy round() function is used to round the elements of an array to the specified number of decimal places. It provides a convenient way to round off floating-point numbers, which can be useful for data normalization, reporting, or simplifying results.

The function rounds values according to the standard rounding rules: values equal to or greater than 0.5 are rounded up, while values less than 0.5 are rounded down. If the number of decimal places is not specified, it rounds to the nearest integer.

Syntax

Following is the syntax of the Numpy round() function −

numpy.round(a, decimals=0)  

Parameters

Following are the parameters of the Numpy round() function −

• a: The input array.
• decimals (optional): The number of decimal places to round to. The default is 0, which rounds to the nearest integer.

Return Type

This function returns a new array with the rounded values.

Example

Following is a basic example of using the Numpy round() function to round the elements of an array −

import numpy as np  
my_Array = np.array([10.123, 20.987, 30.456, 40.789])  
result = np.round(my_Array, 2)  
print("Rounded Array:", result)  

Output

Following is the output of the above code −

Rounded Array: [10.12 20.99 30.46 40.79]  

Example: Rounding to the Nearest Integer

If the number of decimal place is not specified, the function rounds the values to the nearest integer by default −

import numpy as np  
array = np.array([10.8, 20.3, 30.7, 40.1]) 
print("Original Array:",array)
result = np.round(array)  
print("Rounded Array:", result)  

Output

Following is the output of the above code −

Original Array: [10.8 20.3 30.7 40.1]
Rounded Array: [11. 20. 31. 40.]  

Example: Rounding Negative Values

The round() function can also be used to round negative values in an array. Here, when the decimal part of a number is greater than to 0.5, it rounds up to the nearest integer. If the decimal part is less than 0.5, the function rounds down. In this case, we don't specify the number of decimal places, the function will return the rounded integer value −

import numpy as np  
array = np.array([-10.5, -20.3, -30.7, -40.1])  
result = np.round(array)  
print("Rounded Array:", result)  

Output

Following is the output of the above code −

Original Array: [10.8 20.3 30.7 40.1]
Rounded Array: [11. 20. 31. 40.]  

Example: Rounding to a Specific Decimal Places

The round() function allows us to specify the number of decimal places. In the following example, we have rounded the array values to 1 decimal place −

import numpy as np  
array = np.array([10.55, 20.34, 30.89, 40.12])  
result = np.round(array, 1)  
print("Rounded Array:", result)  

Output

Following is the output of the above code −

Rounded Array: [10.6 20.3 30.9 40.1]