How to print numpy array with 3 decimal places?

Learn, how to print numpy array with 3 decimal places in Python?
By Pranit Sharma Last updated : December 21, 2023

NumPy is an abbreviated form of Numerical Python. It is used for different types of scientific operations in python. Numpy is a vast library in python which is used for almost every kind of scientific or mathematical operation. It is itself an array which is a collection of various methods and functions for processing the arrays.

Problem statement

Suppose that we are given a numpy array that contains long decimal values and we need to print its values up to 3 decimal places.

Printing numpy array with 3 decimal places

For this purpose, numpy provides us a simple method called set_printoptions() which we can use and define a lambda function inside it to set the decimal places to 3 points using "{0:0.3f}".format().

This will set numpy to use this lambda function for formatting every float it prints out.

There are certainly other data types that we can define for formatting:

'timedelta' : a `numpy.timedelta64`
'datetime' : a `numpy.datetime64`
'float'
'longfloat' : 128-bit floats
'complexfloat'
'longcomplexfloat' : composed of two 128-bit floats
'numpy_str' : types `numpy.string_` and `numpy.unicode_`
'str' : all other strings

Let us understand with the help of an example,

Python code to print numpy array with 3 decimal places

# Import numpy
import numpy as np

# Creating a numpy array
arr = np.array([0.20424727482457, 0.342095729840246, 0.7690247024585])

# Display original array
print("Original Array:\n",arr,"\n")

# Printing elements of array up to 3 decimal places
np.set_printoptions(formatter={'float': lambda x: "{0:0.3f}".format(x)})

# Display Result
print("Result:\n",arr)