Exercises

1. What is the command to import NumPy as np?

2. Create an array with $10$ zeros.

3. Create an array with $10$ ones.

4. Create an array with $10$ fives.

5. Create a diagonal matrix with $5$ threes down the diagonal.

6. Create an array of the integers from $10$ to $50$.

7. Create an array of the even integers from $10$ to $50$.

8. Create a $3\times 3$ matrix with values ranging from $0$ to $8$.

9. Create the $3\times 3$ identity matrix.

10. Use NumPy to generate a random number between $0$ and $1$.

11. Use NumPy to generate an array of $25$ random numbers sampled from a standard normal distribution.

12. Create The following $10\times 10$ matrix.

    array([[ 0.01,  0.02,  0.03,  0.04,  0.05,  0.06,  0.07,  0.08,  0.09,  0.1 ],
           [ 0.11,  0.12,  0.13,  0.14,  0.15,  0.16,  0.17,  0.18,  0.19,  0.2 ],
           [ 0.21,  0.22,  0.23,  0.24,  0.25,  0.26,  0.27,  0.28,  0.29,  0.3 ],
           [ 0.31,  0.32,  0.33,  0.34,  0.35,  0.36,  0.37,  0.38,  0.39,  0.4 ],
           [ 0.41,  0.42,  0.43,  0.44,  0.45,  0.46,  0.47,  0.48,  0.49,  0.5 ],
           [ 0.51,  0.52,  0.53,  0.54,  0.55,  0.56,  0.57,  0.58,  0.59,  0.6 ],
           [ 0.61,  0.62,  0.63,  0.64,  0.65,  0.66,  0.67,  0.68,  0.69,  0.7 ],
           [ 0.71,  0.72,  0.73,  0.74,  0.75,  0.76,  0.77,  0.78,  0.79,  0.8 ],
           [ 0.81,  0.82,  0.83,  0.84,  0.85,  0.86,  0.87,  0.88,  0.89,  0.9 ],
           [ 0.91,  0.92,  0.93,  0.94,  0.95,  0.96,  0.97,  0.98,  0.99,  1.  ]])
    

13. Create an array of 20 linearly spaced points between 0 and 1.

14. Create a 2D array of numbers from 0 to 49 as follows:

    arr_2d = np.arange(50).reshape(5,10)
    

    Using array slicing write down the command that will produce the following outputs.

    (a)

    Output:
    array([[12, 13, 14, 15],
            [22, 23, 24, 25],
            [32, 33, 34, 35]])
    

    (b)

    Output:
    30
    

    (c)

    Output:
    array([[ 2],
           [12],
           [22],
           [32],
           [42]])
    

15. Create the following matrix.

    mat = np.arange(1,26).reshape(5,5)
    mat
    

    1. Find the sum of all values in mat.
    2. Find the standard deviation of the values in mat.
    3. Find the sum of all columns in mat.