Objects and Data Structures Assessment Test

Test your knowledge.

Answer the following questions

Write a brief description of all the following Object Types and Data Structures we've learned about:

Numbers: represent a whole or floating point value, pos/neg.

Strings: a list of string objects, immutable

Lists: mutable, a collection of one or more types that can be sequenced

Tuples: object representing a number of non-sequenced values

Dictionaries: key-value pairs, not indexed

Numbers

Write an equation that uses multiplication, division, an exponent, addition, and subtraction that is equal to 100.25.

Hint: This is just to test your memory of the basic arithmetic commands, work backwards from 100.25



In [1]:

    
((((10 + 10) * 5) / 10)**2) + 5.00 - 4.75









    Out[1]:





100.25

Explain what the cell below will produce and why. Can you change it so the answer is correct?



In [3]:

    
# Will produce 0 in python 2. produces 0.66 in python 3 because of "true" division
2/3

# the following import will change the outcome
from __future__ import division
2/3









    Out[3]:





0.6666666666666666

Answer these 3 questions without typing code. Then type code to check your answer.

What is the value of the expression 4 * (6 + 5)

What is the value of the expression 4 * 6 + 5 

What is the value of the expression 4 + 6 * 5



In [5]:

    
# 4 * (6 + 5) = 44
4 * (6 + 5)









    Out[5]:





44



In [6]:

    
# 4 * 6 + 5 = 29
4 * 6 + 5









    Out[6]:





29



In [7]:

    
# 4 + 6 * 5 = 34
4 + 6 * 5









    Out[7]:





34

What is the type of the result of the expression 3 + 1.5 + 4? Floating point number, 8.5



In [11]:

    
3 + 1.5 + 4









    Out[11]:





8.5

What would you use to find a number’s square root, as well as its square?



In [10]:

    
#x**y for square, x**0.5 for square root
print(2**2)
print(4**0.5)

Strings

Given the string 'hello' give an index command that returns 'e'. Use the code below:



In [12]:

    
s = 'hello'
# Print out 'e' using indexing

# Code here
print(s[1])

Reverse the string 'hello' using indexing:



In [13]:

    
s ='hello'

# Reverse the string using indexing

# Code here
print(s[::-1])









    



olleh

Given the string hello, give two methods of producing the letter 'o' using indexing.



In [14]:

    
s ='hello'

# Print out the

# Code here
print(s[-1:])
print(s[len(s) - 1])

o
o

Lists

Build this list [0,0,0] two separate ways.



In [15]:

    
print([0,0,0])
print([0] * 3)









    



[0, 0, 0]
[0, 0, 0]

Reassign 'hello' in this nested list to say 'goodbye' item in this list:



In [16]:

    
l = [1,2,[3,4,'hello']]
l[2][2] = "goodbye"
print(l)









    



[1, 2, [3, 4, 'goodbye']]

Sort the list below:



In [22]:

    
l = [3,4,5,5,6]
result = l.sort()
print(result)









    



None

Dictionaries

Using keys and indexing, grab the 'hello' from the following dictionaries:



In [23]:

    
d = {'simple_key':'hello'}
# Grab 'hello'
print(d["simple_key"])









    



hello



In [24]:

    
d = {'k1':{'k2':'hello'}}
# Grab 'hello'
print(d["k1"]["k2"])









    



hello



In [25]:

    
# Getting a little tricker
d = {'k1':[ {'nest_key':['this is deep',['hello']]} ]}

#Grab hello
print(d["k1"][0]["nest_key"][1][0])









    



hello



In [26]:

    
# This will be hard and annoying!
d = {'k1':[
            1,2,{'k2':['this is tricky',{'tough':[1,2,['hello']]}
            ]}
        ]
    }

print(d["k1"][2]["k2"][1]["tough"][2][0])









    



hello

Can you sort a dictionary? Why or why not?

No, dictionaries aren't indexed.

Tuples

What is the major difference between tuples and lists?

mutability: lists are, tuples aren't

How do you create a tuple?



In [27]:

    
tup = (2, "yes", 3.0)
print(tup)









    



(2, 'yes', 3.0)

Sets

What is unique about a set?

non-repeating elements

Use a set to find the unique values of the list below:



In [28]:

    
l = [1,2,2,33,4,4,11,22,3,3,2]
s = set(l)
print(s)









    



set([1, 2, 3, 4, 33, 11, 22])

Booleans

For the following quiz questions, we will get a preview of comparison operators:

Operator	Description	Example
==	If the values of two operands are equal, then the condition becomes true.	(a == b) is not true.
!=	If values of two operands are not equal, then condition becomes true.
<>	If values of two operands are not equal, then condition becomes true.	(a <> b) is true. This is similar to != operator.
>	If the value of left operand is greater than the value of right operand, then condition becomes true.	(a > b) is not true.
<	If the value of left operand is less than the value of right operand, then condition becomes true.	(a < b) is true.
>=	If the value of left operand is greater than or equal to the value of right operand, then condition becomes true.	(a >= b) is not true.
<=	If the value of left operand is less than or equal to the value of right operand, then condition becomes true.	(a <= b) is true.

What will be the resulting Boolean of the following pieces of code (answer fist then check by typing it in!)



In [29]:

    
# Answer before running cell
2 > 3 # False









    Out[29]:





False



In [30]:

    
# Answer before running cell
3 <= 2 # False









    Out[30]:





False



In [31]:

    
# Answer before running cell
3 == 2.0 # False









    Out[31]:





False



In [32]:

    
# Answer before running cell
3.0 == 3 # True









    Out[32]:





True



In [33]:

    
# Answer before running cell
4**0.5 != 2 # False









    Out[33]:





False

Final Question: What is the boolean output of the cell block below?



In [34]:

    
# two nested lists
l_one = [1,2,[3,4]]
l_two = [1,2,{'k1':4}]

#True or False?
l_one[2][0] >= l_two[2]['k1'] # False, 3 >= 4









    Out[34]:





False