6. Strings and dictionaries

Question 1

x = 'Pluto is a planet'
y = "Pluto is a planet"
x == y

True or False?

Answer 1

True

Question 2

The following returns an error. How to fix it?

'Pluto's a planet!'

Answer 2

'Pluto\'s a planet!'

Question 3

How would you do hello world on two separate lines?

Define variable and then print, using double quotes

Answer 3

hello = "hello\nworld"
print(hello)

Question 4

How to do hello world on two separate lines, using triple quotes?

Answer 4

triplequoted_hello = """hello
world"""
print(triplequoted_hello)

Question 5

How do you do 2 separate print statments with words on the same line?

Answer 5

print("hello", end='')
print("pluto", end='')

Question 6

How would you slice the last 3 letters of this word?
planet = 'Pluto'

Answer 6

planet[-3:]

Question 7

How would you turn the following into a list of 5 items, one for each character, each one accompanied by an exclamation mark?
planet = 'Pluto'

Answer 7

[char+'! ' for char in planet]

Question 8

What’s the result of this? and why?
planet[0] = 'B'

Answer 8

TypeError
B/c strings are immutable!

Question 9

How would you turn this into upper case?
claim = "Pluto is a planet!"

Answer 9

claim.upper()

Question 10

How would you find the position of “uto” in the following…

claim = "Pluto is a planet!"

Answer 10

claim.index('uto')

Question 11

How do you create a list of four items from the following?

claim = "Pluto is a planet!"

Answer 11

words = claim.split()

Question 12

How would you split the following into 3 separate variables:

datestr = '1956-01-31'

output variables should be year, month, day

Answer 12

datestr = '1956-01-31'
split_date = datestr.split(sep = "-") 
year, month, day = split_date

Question 13

Join year, month, day into one string, separated by “/”

Answer 13

’/’.join([year,month,day])

Question 14

How do you concantenate “what do you” with b = “mean” with “?”

Answer 14

d = “what do you” + b + “?”

Question 15

b = 10
How would you say that “I am 10 years old”

Using str()

Answer 15

c = "I am " + str(b) + " years old"

Question 16

b = 10
How would you say that “I am 10 years old”

Using .format method

Answer 16

c = "I am {} years old".format(b)

Question 17

What will the following produce?

planet = "Jupiter"
pluto_mass = 1.303 * 10**22
earth_mass = 5.9722 * 10**24
population = 52910390

"{} weighs about {:,.0f} kilograms ({:.3%} of Earth's mass). It is home to {:,} Plutonians.".format(
    planet, pluto_mass, pluto_mass / earth_mass, population,
)

Answer 17

‘Jupiter weighs about 13,029,999,999,999,998,427,136 kilograms (0.218% of Earth’s mass). It is home to 52,910,390 Plutonians.’

Question 18

What does this produce?

# Referring to format() arguments by index, starting from 0
s = """Pluto's a {0}.
No, it's a {1}.
{0}!
{1}!""".format('planet', 'dwarf planet')
print(s)

Answer 18

Pluto’s a planet.
No, it’s a dwarf planet.
planet!
dwarf planet!

Question 19

How do you set up a dictionary with “one” as key and 1 as value, for first 3 numbers?

Answer 19

numbers = {'one':1, 'two':2, 'three':3}

Question 20

How do you access the 2 value from the following?
numbers = {'one':1, 'two':2, 'three':3}

Answer 20

numbers['two']

Question 21

How do you append ‘eleven’ as a key to the following dictionary?
numbers = {'one':1, 'two':2, 'three':3}

Answer 21

numbers['eleven'] = 11

Question 22

How do you change value 1 to “chulent”
numbers = {'one':1, 'two':2, 'three':3}

Answer 22

numbers[‘one’] = ‘chulent’

Question 23

How do you produce the following dictionary from a list of planets?

{'Mercury': 'M',
 'Venus': 'V',
 'Earth': 'E',
 'Mars': 'M',
 'Jupiter': 'J',
 'Saturn': 'S',
 'Uranus': 'U',
 'Neptune': 'N'}

Using a for loop

Answer 23

planets = ['Mercury', 'Venus', 'Earth', 'Mars', 'Jupiter', 'Saturn', 'Uranus', 'Neptune']
planet_to_initial = {planet: planet[0] for planet in planets}
planet_to_initial

Question 24

How do you access the keys, values, and items in a dictionary (“dict”)?

Answer 24

dict.keys
dicts.values
dict.items