Given a 2d numpy array, the task is to flatten a 2d numpy array into a 1d array. Below are a few methods to solve the task.
Method #1 : Using np.flatten()
Python3
# Python code to demonstrate# flattening a 2d numpy array# into 1d arrayimport numpy as npini_array1 = np.array([[1, 2, 3], [2, 4, 5], [1, 2, 3]])# printing initial arraysprint("initial array", str(ini_array1))# Multiplying arraysresult = ini_array1.flatten()# printing resultprint("New resulting array: ", result) |
Output:
initial array [[1 2 3] [2 4 5] [1 2 3]] New resulting array: [1 2 3 2 4 5 1 2 3]
Time complexity: O(n), where n is the total number of elements in the 2D numpy array.
Auxiliary space: O(n), as the result array is also of size n. The flatten function returns a flattened 1D array, which is stored in the “result” variable.
Method #2: Using np.ravel()
Python3
# Python code to demonstrate# flattening a 2d numpy array# into 1d arrayimport numpy as npini_array1 = np.array([[1, 2, 3], [2, 4, 5], [1, 2, 3]])# printing initial arraysprint("initial array", str(ini_array1))# Multiplying arraysresult = ini_array1.ravel()# printing resultprint("New resulting array: ", result) |
Output:
initial array [[1 2 3] [2 4 5] [1 2 3]] New resulting array: [1 2 3 2 4 5 1 2 3]
Method #3: Using np.reshape()
Python3
# Python code to demonstrate# flattening a 2d numpy array# into 1d arrayimport numpy as npini_array1 = np.array([[1, 2, 3], [2, 4, 5], [1, 2, 3]])# printing initial arraysprint("initial array", str(ini_array1))# Multiplying arraysresult = ini_array1.reshape([1, 9])# printing resultprint("New resulting array: ", result) |
Output:
initial array [[1 2 3] [2 4 5] [1 2 3]] New resulting array: [[1 2 3 2 4 5 1 2 3]]
Time Complexity: O(n), where n is the total number of elements in the 2D numpy array.
Auxiliary Space: O(n), as the program creates a new 1D list with the same number of elements as the original 2D array.
