3.md

[*] Indexing

[*] Array Access

• Same as python lists

>>> arr = np.array([1, 2, 3, 4, 5])
>>> print(arr[0])
1
>>> print(arr[4])
5
>>> 
>>> arr = np.array([[6, 3], [0, 2]])
>>> # Subarray
... print(repr(arr[0]))
array([6, 3])
>>> print (arr[0,1])
3
>>> print (arr[0][1])
3

[*] Slicing

• Same as python lists

>>> arr = np.array([1, 2, 3, 4, 5])
>>> print(repr(arr[:]))
array([1, 2, 3, 4, 5])
>>> print(repr(arr[1:]))
array([2, 3, 4, 5])
>>> print(repr(arr[2:4]))
array([3, 4])
>>> print(repr(arr[:-1]))
array([1, 2, 3, 4])
>>> print(repr(arr[-2:]))
array([4, 5])
>>> 

[*] Argmin & Argmax

• These are used to find the index of min and max element of the array.

>>> a = np.array([[np.random.randint(-10,100) for i in range (10)] for j in range(10)])
>>> a
array([[71, 60,  1, -2, 79, 97, 91, 85, 58, 92],
       [-5, 53, 46, 14, -7, 57, 14, 71, 40, 54],
       [16, 37, 41, -2, 50, 51, -8, 36, 49, 61],
       [92, 31, 31,  7, 51, 73,  3, 97, 35, 94],
       [-6, 83, 81, 86, 91, 83, 92, -3, 60, 37],
       [27, 93, 13, 34, 73, 32, 55, 26, 81,  3],
       [96, 12, 18, 75, 25, 90, 75, 41, 67, 49],
       [25, 93, 92, 17, 73, 35, 89, 84, -7, 19],
       [43, 71, 85, 73, 13, -6, 87,  5, 89, 48],
       [91, 12, 47, 24, 36, 42, 68, 92, 83, 30]])
>>> a[0].argmin()
3
>>> a[0].argmax()
5