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| 1 | +import numpy as np |
| 2 | + |
| 3 | +# create one-dimensional array with five elements |
| 4 | +a = np.array([1, 2, 3, 4, 5]) |
| 5 | +print("Array a:", a) |
| 6 | + |
| 7 | +# create 2D array (matrix) of shape 3x3 |
| 8 | +b = np.array([[1, 2, 3], |
| 9 | + [4, 5, 6], |
| 10 | + [7, 8, 9]]) |
| 11 | +print("Matrix b:\n", b) |
| 12 | + |
| 13 | +# array attributes |
| 14 | +print("Shape of b:", b.shape) |
| 15 | +print("Number of dimensions of b:", b.ndim) |
| 16 | +print("Data type of b elements:", b.dtype) |
| 17 | +# convert to float type |
| 18 | +b = b.astype(float) |
| 19 | +print("Converted matrix b to float, new dtype:", b.dtype) |
| 20 | + |
| 21 | +# indexing and slicing |
| 22 | +print("b[0, 0]:", b[0, 0]) |
| 23 | +print("First row of b:", b[0, :]) |
| 24 | +print("Second column of b:", b[:, 1]) |
| 25 | +# slicing with step |
| 26 | +print("Elements of a with step 2:", a[::2]) |
| 27 | + |
| 28 | +# basic array operations |
| 29 | +sum_array = a + np.array([5, 5, 5, 5, 5]) # adding two arrays |
| 30 | +print("a + [5,5,5,5,5]:", sum_array) |
| 31 | + |
| 32 | +scaled = a * 2 # element-wise multiplication by scalar |
| 33 | +print("a * 2:", scaled) |
| 34 | + |
| 35 | +# matrix multiplication (dot product) |
| 36 | +c = np.dot(b, b) |
| 37 | +print("Dot product b * b:\n", c) |
| 38 | + |
| 39 | +# sum of elements |
| 40 | +print("Sum of elements in a:", a.sum()) |
| 41 | +print("Sum of each column in b:", b.sum(axis=0)) |
| 42 | +# example of an invalid axis in sum (to show an error) |
| 43 | +try: |
| 44 | + print("Sum with invalid axis 2:", b.sum(axis=2)) |
| 45 | +except Exception as e: |
| 46 | + print("Error summing along axis 2 (invalid):", e) |
| 47 | + |
| 48 | +# use of universal functions (ufuncs) |
| 49 | +d = np.array([0, np.pi/2, np.pi]) |
| 50 | +print("Angles d:", d) |
| 51 | +print("sin(d):", np.sin(d)) |
| 52 | +print("log of d (with -inf for zero):", np.log(d)) |
| 53 | + |
| 54 | +# broadcasting example |
| 55 | +e = np.arange(1, 4) |
| 56 | +f = np.array([[1], [2], [3]]) |
| 57 | +print("e:", e) |
| 58 | +print("f:", f) |
| 59 | +print("Broadcasted sum e+f:\n", e + f) |
| 60 | + |
| 61 | +# reshape example |
| 62 | +g = np.arange(8) |
| 63 | +g = g.reshape((2,4)) |
| 64 | +print("Reshaped g to 2x4:\n", g) |
| 65 | + |
| 66 | +# simple statistics |
| 67 | +print("Mean of a:", a.mean()) |
| 68 | +print("Standard deviation of g:", g.std()) |
| 69 | + |
| 70 | +# find unique elements |
| 71 | +h = np.array([1, 2, 2, 3, 3, 3]) |
| 72 | +print("Unique elements in h:", np.unique(h)) |
| 73 | + |
| 74 | +# sort elements of an array in descending order |
| 75 | +print("Sorted a in descending:", np.sort(a)[::-1]) |
| 76 | + |
| 77 | +# random array example |
| 78 | +np.random.seed(0) |
| 79 | +rand_arr = np.random.rand(3, 3) |
| 80 | +print("Random array:", rand_arr) |
| 81 | + |
| 82 | +# element-wise comparison |
| 83 | +print("Elements of rand_arr > 0.5:\n", rand_arr > 0.5) |
| 84 | + |
| 85 | +# creating arrays using linspace |
| 86 | +lin = np.linspace(0, 1, 5) |
| 87 | +print("Linearly spaced array:", lin) |
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