# Appending values at the end of an NumPy array

• Difficulty Level : Easy
• Last Updated : 02 Sep, 2020

Let us see how to append values at the end of a NumPy array. Adding values at the end of the array is a necessary task especially when the data is not fixed and is prone to change. For this task we can use numpy.append(). This function can help us to append a single value as well as multiple values at the end of the array.

Syntax : numpy.append(array, values, axis = None)
Parameters :

• array : Input array.
• values : values to be added in the array.
• axis : Axis along which we want to insert the values.

Returns : An copy of array with values being appended at the end as per the mentioned object
along a given axis.

Examples 1 : Appending a single value to a 1D array. For 1D array, using the axis argument is not necessary as the array is flattened by default.

 `# importing the module``import` `numpy as np`` ` `# creating an array``arr ``=` `np.array([``1``, ``8``, ``3``, ``3``, ``5``])``print``(``'Original Array : '``, arr)`` ` `# appending to the array``arr ``=` `np.append(arr, [``7``])``print``(``'Array after appending : '``, arr)`

Output :

```Original Array :  [1 8 3 3 5]
Array after appending :  [1 8 3 3 5 7]
```

Example 2 : Appending another array at the end of 1D array. You may pass a list or an array to the append function, the result will be the same.

 `# importing the module``import` `numpy as np`` ` `# creating an array``arr1 ``=` `np.array([``1``, ``2``, ``3``])``print``(``'First array is : '``, arr1)`` ` `# creating another array``arr2 ``=` `np.array([``4``, ``5``, ``6``])``print``(``'Second array is : '``, arr2)`` ` `# appending arr2 to arr1``arr ``=` `np.append(arr1, arr2)``print``(``'Array after appending : '``, arr)`

Output :

```First array is :  [1 2 3]
Second array is :  [4 5 6]
Array after appending :  [1 2 3 4 5 6]
```

Example 3 : Appending values at the end of the n-dimensional array. It is important that the dimensions of both the array matches otherwise it will give an error.

 `# importing the module``import` `numpy as np`` ` `# create an array``arr ``=` `np.arange(``1``, ``13``).reshape(``2``, ``6``)``print``(``'Original Array'``)``print``(arr, ``'\n'``)`` ` `# create another array which is``# to be appended column-wise``col ``=` `np.arange(``5``, ``11``).reshape(``1``, ``6``)``print``(``'Array to be appended column wise'``)``print``(col)``arr_col ``=` `np.append(arr, col, axis ``=` `0``)``print``(``'Array after appending the values column wise'``)``print``(arr_col, ``'\n'``)`` ` `# create an array which is``# to be appended row wise``row ``=` `np.array([``1``, ``2``]).reshape(``2``, ``1``)``print``(``'Array to be appended row wise'``)``print``(row)``arr_row ``=` `np.append(arr, row, axis ``=` `1``)``print``(``'Array after appending the values row wise'``)``print``(arr_row)`

Output :

```Original Array
[[ 1  2  3  4  5  6]
[ 7  8  9 10 11 12]]

Array to be appended column wise
[[ 5  6  7  8  9 10]]
Array after appending the values column wise
[[ 1  2  3  4  5  6]
[ 7  8  9 10 11 12]
[ 5  6  7  8  9 10]]

Array to be appended row wise
[[1]
[2]]
Array after appending the values row wise
[[ 1  2  3  4  5  6  1]
[ 7  8  9 10 11 12  2]]
```

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