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Parameters Return value Examples Appending to a 1D array Appending rows to a 2D array Appending a single row Appending multiple rows Appending columns to a 2D array Appending a single column Appending multiple columns

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NumPy | append method

schedule Aug 12, 2023

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Parameters Return value Examples Appending to a 1D array Appending rows to a 2D array Appending a single row Appending multiple rows Appending columns to a 2D array Appending a single column Appending multiple columns

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Numpy's append(~) method returns a new Numpy array with the specified values appended to the input array.

Parameters

1. a | array_like

The source array.

2. values | array_like

The values to append to the source array.

3. axis | int | optional

The axis along which to perform the append. For 2D arrays, the allowed values and their meaning are:

Axis	Meaning
0	Appending rows
1	Appending columns
None	Appending into a flattened array

By default, axis=None.

Return value

A new Numpy array with the specified values appended to a.

Examples

Appending to a 1D array


        
        
            
                
                
                    a = np.array([3,4,5])
np.append(a, 8)
                
            
            array([3, 4, 5, 8])

Appending to a 2D array

Consider the following array:


        
        
            
                
                
                    a = np.array([[3,4],[5,6]])
a
                
            
            array([[3, 4],
       [5, 6]])

Appending to a flattened 2D array


        
        
            
                
                
                    np.append(a, [8,9])
                
            
            array([3, 4, 5, 6, 8, 9])

Appending rows to a 2D array

Considering the following array:


        
        
            
                
                
                    a = np.array([[3,4],[5,6]])
a
                
            
            array([[3, 4],
       [5, 6]])

Appending a single row


        
        
            
                
                
                    np.append(a, [[8,9]], axis=0)      # axis=0 represents row appends
                
            
            array([[3, 4],
       [5, 6],
       [8, 9]])

Appending multiple rows


        
        
            
                
                
                    np.append(a, [[8,9], [10,11]], axis=0)
                
            
            array([[ 3,  4],
       [ 5,  6],
       [ 8,  9],
       [10, 11]])

Appending columns to a 2D array

Considering the following array:


        
        
            
                
                
                    a = np.array([[3,4],[5,6]])
a
                
            
            array([[3, 4],
       [5, 6]])

Appending a single column


        
        
            
                
                
                    np.append(a, [[8],[9]], axis=1)
                
            
            array([[3, 4, 8],
       [5, 6, 9]])

Appending multiple columns


        
        
            
                
                
                    np.append(a, [[8,9],[10,11]], axis=1)
                
            
            array([[ 3,  4,  8,  9],
       [ 5,  6, 10, 11]])

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Published by Isshin Inada

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