Python Basics

(adapted from Quantecon)

Basics

Exercise 1 Run the following code in the python interpreter:

def say_hello(name):
    """This function prints morning greetings"""

    print(f"Good morning {name}!\n")

    # we can import libraries
    import datetime
    t = datetime.datetime.now()

    # blocks are defined by indentation and colons
    if (t.hour,t.min) <= (9,15):
        print("All good?\n")
    else:
        print("Time to get started?\n")


say_hello("Pablo")

Exercise 2 What do you think the value of z is after running the code below?

z = 3
z = z + 4
print("z is", z)

z is 7

# your response there

Exercise 3 Read about what the len function does (by writing len?).

What will it produce if we give it the variable x?

Check whether you were right by running the code len(x).

# your code here

Exercise 4 We can use our introspection skills to investigate a package’s contents.

In the cell below, use tab completion to find a function from the time module that will display the local time.

Use time.FUNC_NAME? (where FUNC_NAME is replaced with the function you found) to see information about that function and then call the function.

Look for something to do with the word local

import time
# your code here

Exercise 5 The code below is invalid Python code (once uncommented)

# x = 'What's wrong with this string'

Collections

Exercise 6 In the first cell, try y.append(z).

In the second cell try y.extend(z).

Explain the behavior.

When you are trying to explain use y.append? and y.extend? to see a description of what these methods are supposed to do.

y = ["a", "b", "c"]
z = [1, 2, 3]
# 

y = ["a", "b", "c"]
z = [1, 2, 3]
# 

Exercise 7 Verify that tuples are indeed immutable by attempting the following:

• Changing the first element of t to be 100
  
• Appending a new element "!!" to the end of t (remember with a list x we would use x.append("!!") to do this
  
• Sorting t
  
• Reversing t

t = (1,2,3,4)

Exercise 8 Look at the World Factbook for Australia and create a dictionary with data containing the following types: float, string, integer, list, and dict. Choose any data you wish.

To confirm, you should have a dictionary that you identified via a key.

# your code here

Exercise 9 Use Jupyter’s help facilities to learn how to use the pop method to remove the key "irrigated_land" (and its value) from the dict.

# uncomment and use the Inspector or ?
#china_data.pop()

Exercise 10 Explain what happens to the value you popped.

Experiment with calling pop twice.

# your code here

Control

Exercise 11 Run the following two variations on the code with only a single change in the indentation.

After, modify the x to print 3 and then 2, 3 instead.

x = 1

if x > 0:
    print("1")
    print("2")
print("3")

1
2
3

x = 1

if x > 0:
    print("1")
print("2") # changed the indentation
print("3")

1
2
3

Exercise 12 Write a for loop that uses the lists of cities and states below to print the same “{city} is in {state}” using a zip instead of an enumerate.

cities = ["Phoenix", "Austin", "San Diego", "New York"]
states = ["Arizona", "Texas", "California", "New York"]

for i,c in enumerate(cities):
    print(c, " : ", states[i])

Phoenix  :  Arizona
Austin  :  Texas
San Diego  :  California
New York  :  New York

# your code here