Grok Worksheet 2

Question 1

What is the structure of an expression in Python?

Answer 1

operand_1 operator operand_2

Question 2

Give an example of a symbol that does not form an expression.

Answer 2

Assignment (‘=’) is not an expression, so it can not be used like y = 1 + ( x = 4)

Question 3

List the three array-type operands in Python.

Answer 3

Tuples = tuple() : (1, 2, 3) or ('apple', 3.1415)
Lists = list() : [1,1,2,3,5] or ['a','b','c','d']
Dictionaries = dict() : {"name" : "Bob", "age" : 45}

Question 4

What type is used to represent positive or negative whole numbers?

Answer 4

Integers: int

Question 5

What type is used to represent positive or negative numbers with a decimal component?

Answer 5

Floating point: float

Question 6

Other than using a decimal, how else can we create a floating point number?

Answer 6

Using scientific notation:
>>> print(1e4) # 1e4 = 1 x 10 ** 4
10000.0
>>> print(1.23e-2)
0.0123

Question 7

Fill in and explain the result:

|&raquo_space;> print(3 / 4, type(3/4))

Answer 7

0.75

Python will implicitly convert integers to floats when using (true) division on integers.

Question 8

How can we modify the following line to yield an integer and type = int:
»> print(3 / 4, type(3/4))

Answer 8

> > > print(3 // 4, type(3 / /4)) # Floored division
0
print(int(3 / 4), type((int3 /4))) # Floored division
0

Question 9

What is ‘type casting’?

Answer 9

Converting one type into another, if possible. Eg:
»> a = str(123)
‘123’
»> type(a)

Question 10

> > > print(int(“32.7”)) # What will this return?

Answer 10

> > > print(int(“32.7”)) # ‘.’ is not a number

ValueError: invalid literal for int() with base 10: ‘32.7’

Question 11

> > > print(float(“32.7”)) # What will this return?

Answer 11

> > > print(float(“32.7”)) # Unlike int(), float() can handle ‘.’
32.7

Question 12

> > > print(str(123) + str(456)) # What will this return?

Answer 12

> > > print(str(123) + str(456))

123456

Question 13

True or false: modulo and floored division only work on type int.

Answer 13

False, they also work on type float.