NumPy Array Indexing

Question 1

arr = np.arange(0,11)
:

arr[8]

Answer 1

8

Question 2

arr = np.arange(0,11)
:

arr[0:5]

Answer 2

array([0, 1, 2, 3, 4])

Question 3

arr = np.arange(0,11)
:

array[5:]

Answer 3

array([5, 6, 7, 8, 9, 10])

Question 4

arr = np.arange(0,11) :
arr[0:5] = 100

arr

Answer 4

array([100, 100, 100, 100, 100, 6, 7, 8, 9, 10)]

Question 5

arr = np.arange(0,11) :
slice_of_arr = arr[0:6]
slice_of_arr[:] = 99

arr

Answer 5

array([99, 99, 99, 99, 99])

array([99, 99, 99, 99, 99, 6, 7, 8, 9, 10])

Question 6

arr = np.arange(0,11) :

arr_copy = arr.copy()
arr_copy[:] = 100

arr
arr_copy

Answer 6

array([1, 2, 3, 4, 5, 6, 7, 8, 9, 10])

array[100, 100, 100, 100, 100, 100, 100, 100, 100, 100])

Question 7

arr_2d = np.array([[5,10,15],[20,25,30],[35,40,45]])

arr_2d[0]

Answer 7

array([ 5, 10, 15])

Question 8

arr_2d = np.array([[5,10,15],[20,25,30],[35,40,45]])

arr_2d[1][1]

Answer 8

25

Question 9

arr_2d = np.array([[5,10,15],[20,25,30],[35,40,45]])

arr_2d[1,2]

Answer 9

30

Question 10

arr_2d = np.array([[5,10,15],[20,25,30],[35,40,45]])

arr_2d[:2,1:]

Answer 10

array([[10, 15],
[25, 30]])

Question 11

arr_2d = np.array([[5,10,15],[20,25,30],[35,40,45]])

arr_2d[:2]

Answer 11

array([[5, 10, 15],
[20, 25, 30]])

Question 12

arr_2d = np.array([[5,10,15],[20,25,30],[35,40,45]])

arr_2d[1:,1:]

Answer 12

array([[25, 30],
[35, 40]])

Question 12

arr = np.arange(1,11)
arr > 5
bool_arr = arr

bool_arr

Answer 12

array([False, False, False, False, False, True, True, True, True, True])

Question 13

arr = np.arange(1,11)
arr > 5
bool_arr = arr

arr[bool_arr]

Answer 13

array[ 6, 7, 8, 9, 10]

Question 14

arr = np.arange(1,11)
arr[arr>5]

Answer 14

array[ 6, 7, 8, 9, 10]