Add columns in the Numpy array
Method 1: Using np.append()
Python3
import numpy as npini_array = np.array([[1, 2, 3], [45, 4, 7], [9, 6, 10]])# printing initial arrayprint("initial_array : ", str(ini_array));# Array to be added as columncolumn_to_be_added = np.array([[1], [2], [3]])# Adding column to array using append() methodarr = np.append(ini_array, column_to_be_added, axis=1)# printing resultprint ("resultant array", str(arr)) |
Output:
initial_array : [[ 1 2 3] [45 4 7] [ 9 6 10]] resultant array [[ 1 2 3 1] [45 4 7 2] [ 9 6 10 3]]
Method 2: Using np.concatenate
Python3
import numpy as npini_array = np.array([[1, 2, 3], [45, 4, 7], [9, 6, 10]])# Array to be added as columncolumn_to_be_added = np.array([[1], [2], [3]])# Adding column to array using append() methodarr = np.concatenate([ini_array, column_to_be_added], axis=1)# printing resultprint ("resultant array", str(arr)) |
Output:
resultant array [[ 1 2 3 1] [45 4 7 2] [ 9 6 10 3]]
Method 3: Using np.insert()
Python3
import numpy as npini_array = np.array([[1, 2, 3], [45, 4, 7], [9, 6, 10]])# Array to be added as columncolumn_to_be_added = np.array([[1], [2], [3]])# Adding column to array using append() methodarr = np.insert(ini_array, 0, column_to_be_added, axis=1)# printing resultprint ("resultant array", str(arr)) |
Output:
resultant array [[ 1 2 3 1] [45 4 7 2] [ 9 6 10 3]]
Method 4: Using np.hstack()
Python3
import numpy as npini_array = np.array([[1, 2, 3], [45, 4, 7], [9, 6, 10]])# Array to be added as columncolumn_to_be_added = np.array([1, 2, 3])# Adding column to numpy arrayresult = np.hstack((ini_array, np.atleast_2d(column_to_be_added).T))# printing resultprint ("resultant array", str(result)) |
Output:
resultant array [[ 1 2 3 1] [45 4 7 2] [ 9 6 10 3]]
Method 5: Using np.column_stack()
Python3
import numpy as npini_array = np.array([[1, 2, 3], [45, 4, 7], [9, 6, 10]])# Array to be added as columncolumn_to_be_added = np.array([1, 2, 3])# Adding column to numpy arrayresult = np.column_stack((ini_array, column_to_be_added))# printing resultprint ("resultant array", str(result)) |
Output:
resultant array [[ 1 2 3 1] [45 4 7 2] [ 9 6 10 3]]
Python | Ways to add row/columns in numpy array
Given a Numpy array, the task is to add rows/columns basis on requirements to the Numpy array. Let’s see a few examples of this problem in Python.