How to give input to an array in Python

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1. Python add to Array

• If you are using List as an array, you can use its append(), insert(), and extend() functions. You can read more about it at Python add to List.
• If you are using array module, you can use the concatenation using the + operator, append(), insert(), and extend() functions to add elements to the array.
• If you are using NumPy arrays, use the append() and insert() function.

2. Adding elements to an Array using array module

• Using + operator: a new array is returned with the elements from both the arrays.
• append(): adds the element to the end of the array.
• insert(): inserts the element before the given index of the array.
• extend(): used to append the given array elements to this array.

1. import array 
2.  
3. arr1 = array.array('i', [1, 2, 3]) 
4. arr2 = array.array('i', [4, 5, 6]) 
5.  
6. print(arr1) # array('i', [1, 2, 3]) 
7. print(arr2) # array('i', [4, 5, 6]) 
8.  
9. arr3 = arr1 + arr2 
10. print(arr3) # array('i', [1, 2, 3, 4, 5, 6]) 
11.  
12. arr1.append(4) 
13. print(arr1) # array('i', [1, 2, 3, 4]) 
14.  
15. arr1.insert(0, 10) 
16. print(arr1) # array('i', [10, 1, 2, 3, 4]) 
17.  
18. arr1.extend(arr2) 
19. print(arr1) # array('i', [10, 1, 2, 3, 4, 4, 5, 6]) 

3. Adding elements to the NumPy Array

• append(): the given values are added to the end of the array. If the axis is not provided, then the arrays are flattened before appending.
• insert(): used to insert values at the given index. We can insert elements based on the axis, otherwise, the elements will be flattened before the insert operation.

1. >>> import numpy as np 
2. >>> np_arr1 = np.array([[1, 2], [3, 4]]) 
3. >>> np_arr2 = np.array([[10, 20], [30, 40]]) 
4. >>>  
5. >>> np.append(np_arr1, np_arr2) 
6. array([ 1, 2, 3, 4, 10, 20, 30, 40]) 
7. >>> 
8. >>> np.append(np_arr1, np_arr2, axis=0) 
9. array([[ 1, 2], 
10. [ 3, 4], 
11. [10, 20], 
12. [30, 40]]) 
13. >>> 
14. >>> np.append(np_arr1, np_arr2, axis=1) 
15. array([[ 1, 2, 10, 20], 
16. [ 3, 4, 30, 40]]) 
17. >>>  
18. >>> np.insert(np_arr1, 1, np_arr2, axis=0) 
19. array([[ 1, 2], 
20. [10, 20], 
21. [30, 40], 
22. [ 3, 4]]) 
23. >>>  
24. >>> np.insert(np_arr1, 1, np_arr2, axis=1) 
25. array([[ 1, 10, 30, 2], 
26. [ 3, 20, 40, 4]]) 
27. >>>