Python | Flatten a 2D Numpy Array into 1D Array Last Updated : 10 Dec, 2025 Comments Improve Suggest changes 8 Likes Like Report Given a 2D NumPy array, the task is to convert it into a 1D array. Flattening helps when you want to convert matrix-style data into a single list-like structure for further processing. For Example:Input: [[1, 2], [3, 4]]Output: [1 2 3 4]Let's explore different ways to flatten a 2D NumPy array into a 1D array.Using np.ravel() ravel() tries to return a view of the original array (not a copy). It reads values row-wise and presents them as a 1D array, making it the most efficient method. Python import numpy as np a = np.array([[1, 2, 3], [4, 5, 6]]) res = a.ravel() print(res) Output[1 2 3 4 5 6] Using np.ndarray.flatten() flatten() creates a new copy of the data and converts the array into a row-major 1D array. Python import numpy as np a = np.array([[1, 2, 3], [4, 5, 6]]) res = a.flatten() print(res) Output[1 2 3 4 5 6] Using reshape(-1)reshape(-1) converts any array into a 1D array. The -1 tells NumPy to automatically compute the required length. Python import numpy as np a = np.array([[1, 2, 3], [4, 5, 6]]) res = a.reshape(-1) print(res) Output[1 2 3 4 5 6] Explanation:a.reshape(-1) reshapes the structure into one dimension.-1 NumPy figures out the correct final size on its own.Using np.concatenate() concatenate() joins all inner arrays (rows) one after another, forming a single continuous 1D array. Python import numpy as np a = np.array([[1, 2, 3], [4, 5, 6]]) res = np.concatenate(a) print(res) Output[1 2 3 4 5 6] Explanation: np.concatenate(a) combines each row from a into one long array. Create Quiz Comment G garg_ak0109 Follow 8 Improve G garg_ak0109 Follow 8 Improve Article Tags : Python Python-numpy Python numpy-program Explore Python FundamentalsPython Introduction 2 min read Input and Output in Python 4 min read Python Variables 4 min read Python Operators 4 min read Python Keywords 2 min read Python Data Types 8 min read Conditional Statements in Python 3 min read Loops in Python - For, While and Nested Loops 5 min read Python Functions 5 min read Recursion in Python 4 min read Python Lambda Functions 5 min read Python Data StructuresPython String 5 min read Python Lists 4 min read Python Tuples 4 min read Python Dictionary 3 min read Python Sets 6 min read Python Arrays 7 min read List Comprehension in Python 4 min read Advanced PythonPython OOP Concepts 11 min read Python Exception Handling 5 min read File Handling in Python 4 min read Python Database Tutorial 4 min read Python MongoDB Tutorial 3 min read Python MySQL 9 min read Python Packages 10 min read Python Modules 3 min read Python DSA Libraries 15 min read List of Python GUI Library and Packages 3 min read Data Science with PythonNumPy Tutorial - Python Library 3 min read Pandas Tutorial 4 min read Matplotlib Tutorial 5 min read Python Seaborn Tutorial 3 min read StatsModel Library - Tutorial 3 min read Learning Model Building in Scikit-learn 6 min read TensorFlow Tutorial 2 min read PyTorch Tutorial 6 min read Web Development with PythonFlask Tutorial 8 min read Django Tutorial | Learn Django Framework 7 min read Django ORM - Inserting, Updating & Deleting Data 4 min read Templating With Jinja2 in Flask 6 min read Django Templates 5 min read Build a REST API using Flask - Python 3 min read Building a Simple API with Django REST Framework 3 min read Python PracticePython Quiz 1 min read Python Coding Practice 1 min read Python Interview Questions and Answers 15+ min read Like