Python Basic Exercises

Question 1

Predict the output of the following code blocks? Run them in Colab to check if your predictions were correct?

Note: You might have to look on the internet for the meaning of some symbols (such as / and %)

7 / 3 == 7 / 3.0

True

'nesia' in 'Indonesia'

True

(2 + 3) == 5

True

2 + 3 == 5

True

"2" + "3" == "5"

False

11 % 3

2

1 < 2 and 11 >= 9

True

2 > 5 or (1 < 2 and 11 >= 9)

True

Question 2

Modify the above code to print ‘Hello Hello Hello Hello Batman’ when the name is ‘Batman.’

name = 'Batman'

if name == 'Batman':
   print('Hello '*5 + 'Batman!')
else:
   print('Hello World!')

Hello Hello Hello Hello Hello Batman!

Modify the code to respond to Robin instead of Batman.

name = 'Robin'

if name == 'Robin':
   print('Hello '*5 + 'Robin!')
else:
   print('Hello World!')

Hello Hello Hello Hello Hello Robin!

Question 3

The following code has a few bugs; fix them!

import math
x,y = 3,4
z = math.sqrt(x**2 + y**2)
print(x,y,z)

3 4 5.0

Question 4

import numpy as np

my_np_list = np.array([182, 269, 341, 410, 523,
                       697, 728, 856, 948, 101,
                       1120, 1272, 1312, 1460, 1564,
                       1642, 1717, 1816, 1923, 2087])                

1. What is the number in the 4th position in the array?

my_np_list[3]

410

1. What is the last number in the array?

my_np_list[-1]

2087

1. What are the first 3 values?

my_np_list[:3]

array([182, 269, 341])

1. What are the values from the 4th to the 10th position? (This should include the numbers at the 4th and 10th positions.)

my_np_list[3:10]

array([410, 523, 697, 728, 856, 948, 101])

1. What are the values in the list greater than 500?

my_np_list[my_np_list > 500]

array([ 523,  697,  728,  856,  948, 1120, 1272, 1312, 1460, 1564, 1642,
       1717, 1816, 1923, 2087])

1. Use the 'hidden' numpy functions max(), min(), mean() and std() to find the maximum, minimum, mean and standard deviation of the values of the numpy array.

my_np_list.max()

2087

my_np_list.min()

101

my_np_list.mean()

1048.4

my_np_list.std()

612.5768849703685

1. Make all the numbers less than 500 equal to zero!

my_np_list[my_np_list < 500] = 0

my_np_list                        # Did it work?

array([   0,    0,    0,    0,  523,  697,  728,  856,  948,    0, 1120,
       1272, 1312, 1460, 1564, 1642, 1717, 1816, 1923, 2087])

1. What are the values in the list greater than 500 and less than 1000?

Note

• You cannot use 'and' how arrays are setup internally! You need to use '&'.
• If it was an 'or' the symbol will be '|' so that:

  (my_np_list > 500) | (my_np_list < 1000)

my_np_list[(my_np_list > 500) & (my_np_list < 1000)]

array([523, 697, 728, 856, 948])