Mod 4 Flashcards
Where can functions come from? (3)
- Built in functions from Python (for example print())
- Python’s preinstalled modules have functions
- The user can write their own functions
Write the code that builds a function named fun and prompts the user to input their name, and then thanks them and prints the name. Make sure to invoke the function.
def fun():
a = input('What is your name?')
print('Thanks', a)
fun()
What are the rules about functions (2)?
- Cannot invoke a function which is not known at the moment of invocation
- Cannot have a function and a variable of the same name
Where in the function is a parameter defined?
def function(parameter) inside the parenthesis
What is the difference between a parameter and argument?
Parameters exist inside functions
arguments exist outside functions
what is the output of the below code:
def message(number):
print("Enter a number:", number)
message()
TypeError: message() missing 1 required positional argument: ‘number’
What type of parameters are in the below function?
def myFunction(a, b, c):
print(a, b, c)
myFunction(1, 2, 3)
positional parameters
What type of parameters are in the below function?
def introduction(firstName, lastName):
print("Hello, my name is", firstName, lastName)
introduction(firstName = "James", lastName = "Bond") introduction(lastName = "Skywalker", firstName = "Luke")
keyword parameters
What is the output of:
def intro(a, b="Bond"):
print("My name is", b + ".", a + ".")
intro(“Susan”)
My name is Bond. Susan.
What is the output of:
def sum(a, b=2, c):
print(a + b + c)
sum(a=1, c=3)
SyntaxError - a non-default argument (c) follows a default argument (b=2)
What is the output of:
def subtra(a, b):
print(a - b)
subtra(5, b=2)
subtra(a=5, 2)
3
Syntax Error positional argument follows a keyword argument
What does the “return” function do? What happens to the code after the return function? What if nothing is assigned to it?
It ends the execution of the function and returns the result. Everything after the return statement is not executed. If a value isnt assigned to the return instruction, it returns “None”
“None” facts/rules (3) and when can it be used (2)?
- it doesnt hold a value
- it must not be used in an expression
- It is a keyword
- when it is assigned to a variable
- when it is compared to a variable
Can a single integer be iterated through the for loop?
No
What is the output of:
def multiply(a, b):
return
print(multiply(3, 4))
None
What is the output of:
def wishes():
print("My Wishes")
return "Happy Birthday"
wishes()
My Wishes
What is the output of:
def wishes():
print("My Wishes")
return "Happy Birthday"
print(wishes())
My Wishes
Happy Birthday
What is the output of:
def hi():
return
print("Hi!")
hi()
None
What is the output of:
def isInt(data):
if type(data) == int:
return True
elif type(data) == float:
return False
print(isInt(5))
print(isInt(5.0))
print(isInt(“5”))
True
False
None
What is the output of:
def myFunction():
global var
var = 2
print("Do I know that variable?", var)
var = 1
myFunction()
print(var)
Do I know that variable? 2
2
What is the output of:
def myFunction(myList1):
print(myList1)
myList1 = [0, 1]
myList2 = [2, 3]
myFunction(myList2)
print(myList2)
[2, 3]
[2, 3]
What is the output of:
def myFunction(myList1):
print(myList1)
del myList1[0]
myList2 = [2, 3]
myFunction(myList2)
print(myList2)
[2, 3]
[3]
A variable that exists outside a function has a scope inside the function body unless when?
The function defines a variable of the same name
True or False: A variable that exists inside a function has a scope inside the function body
True
What does the global keyword do?
It makes the variable’s scope global (used inside or outside of a function)
What is the output of:
def message():
alt = 1
print("Hello, World!")
print(alt)
NameError: name “alt” is not defined
What is the output of:
a = 1
def fun():
global a
a = 2
print(a)
a = 3
fun()
print(a)
2
2
What is the output of:
def factorialFun(n):
if n < 0:
return None
if n < 2:
return 1
return n * factorialFun(n - 1)
print(factorialFun(5))
120
because 54321 = 120
What is it called when a function calls itself?
recursion
What is a function that calls itself and contains a specified termination condition?
recursive
What is the output of:
def factorial(n):
return n * factorial(n - 1)
print(factorial(4))
RecursionError: maximum recursion depth exceeded
What is the output of:
def fun(a):
if a > 30:
return 3
else:
return a + fun(a + 3)
print(fun(25))
56
What is a sequence data type?
Is a type of data which is able to store more than one value, these values can be sequentially browsed.
What is mutability?
property of Python’s data that describes its readiness to be free changed during program execution.
Mutable data - can be freely updated at any time
Immutable data - restricted in how it can be updated
list.append(1) - acceptable for mutable data, but not immutable.
Facts about tuples (5):
- Immutable sequence type
- created by values in parenthesis or separated by commas (value1, value2) or value1, value2
- can contain int, float, string, Boolean
- can appear on the left side of the =
- tuples elements can be variables (not just literals)
Write the code showing 2 ways of creating a single element tuple
(1, )
1,
What is the output of:
myTuple = (1, 10, 100, 1000)
myTuple.append(10000)
AttributeError: ‘tuple’ object has no attribute ‘append’
When applied to tuples, what does * and + do?
- replicates the tuple
+ concatenates the tuple
Facts about dictionaries (3) and rule (1)
- not a sequence and is mutable
- created by keys and values separated by colons, pairs separated by commas, surrounded by curly braces
- set of key-value pairs
- each key must be unique and can be of any data type
Write the code to print the value for cat:
dictionary = {“cat” : “chat”, “dog” : “chien”, “horse” : “cheval”}
print(dictionary[“cat”])
output: chat
Write a for loop so that the key value pairs of the dictionary can be seen:
dictionary = {“cat” : “chat”, “dog” : “chien”, “horse” : “cheval”}
for key in dictionary.keys():
print(key, "->", dictionary[key])
(output:
cat -> chat
dog -> chien
horse -> cheval)Write the code to sort the dictionary:
dictionary = {“cat” : “chat”, “dog” : “chien”, “horse” : “cheval”}
for key in sorted(dictionary.keys()):
print(key, "->", dictionary[key])
(output:
cat -> chat
dog -> chien
horse -> cheval)Write the code to use the items() method to return the dictionary as tuples:
dictionary = {“cat” : “chat”, “dog” : “chien”, “horse” : “cheval”}
for english, french in dictionary.items():
print(english, "->", french)
(output:
cat -> chat
dog -> chien
horse -> cheval)Add the key swan and value cygne to the dictionary:
dictionary = {“cat” : “chat”, “dog” : “chien”, “horse” : “cheval”}
dictionary[‘swan’] = ‘cygne’
Write the code that deletes the dog key-value pair:
dictionary = {“cat” : “chat”, “dog” : “chien”, “horse” : “cheval”}
del dictionary[‘dog]
What do the clear(), copy(), get(), update() and popitem() methods do to a dictionary?
clear() removes all items from the dictionary
copy() copies the dictionary
get() allows access to a dictionary item (value) by referencing the key
update() inserts an item into the dictionary
popitem() removes the last element
What is the output of:
tup = 1, 2, 3
a, b, c = tup
print(a * b * c)
6
What do the dict, tuple and list functions do?
dict - converts to a dictionary
tuple - converts to a tuple
list - converts to a list
