🧳 Part 1: Day 1 - 3
🧳 Part 2: Day 4 - 6
🧳 Part 3: Day 7 - 9
🧳 Part 4: Day 10 - 12
🧳 Part 5: Day 13 - 15
🧳 Part 6: Day 16 - 18
🧳 Part 7: Day 19 - 21
🧳 Part 8: Day 22 - 24
🧳 Part 9: Day 25 - 27
🧳 Part 10: Day 28 - 30
- 📘 Day 7
- Set
- Creating a set
- Getting set length
- Accessing Items in set
- Checking an item
- Adding items to a list
- Removing item from a list
- Clearing item in a set
- Deleting a set
- Converting list to set
- Joining sets
- Finding intersection items
- Checking subset and super set
- Checking difference between two sets
- Finding Symmetric difference between two sets
- Joining set
- 💻 Exercises: Day 7
- 📘 Day 8
- Dictionary
- Creating a dictionary
- Dictionary Length
- Accessing a dictionary items
- Adding Item to a dictionary
- Modifying Item in a dictionary
- Checking a key in a dictionary
- Removing key items from dictionary
- Changing dictionary to list items
- Clearing dictionary list items
- Deleting dictionary
- Copy a dictionary
- Getting dictionary keys as list
- Getting dictionary values as list
- 💻 Exercises: Day 8
- 📘 Day 9
- Conditionals
- 💻 Exercises: Day 9
📘 Day 7
Set
Let me take you back to your elementary or high school Mathematics lesson. The Mathematics definition of set can be applied also in python. Set is a collection of unordered and unindexed distinct elements. In python set uses to store unique items, and it is possible to find the union, intersection, difference, symmetric difference, subset, super set and disjoint set among sets.
Creating a set
We use curly bracket, {} to create a set. * Creating an empty set
* Creating a set with initial items Example:Getting set length
We use len() method to find the length of a set.
Example:Accessing Items in set
We use loops to access items. We will see this in loop section
Checking an item
To check if an item exist in a list use use in.
Example:Adding items to a list
Once a list is created we can not change an item but we can add additional items. * Add one item using add()
Example: * Add multiple items or using update() Example:fruits = {'banana', 'orange', 'mango', 'lemon'}
vegetables = ('Tomato', 'Potato', 'Cabbage','Onion', 'Carrot')
fruits.update(vegetables)
Removing item from a list
We can remove an item from a list using remove() method. If the item is not found remove() method raise an errors, so it is good to check if the item exist or not. However, discard() method doesn't raise an error. Example:*
Clearing item in a set
If we want to clear or empty the set we use clear method.
Example:Deleting a set
If we want to delete the set itself we use del operator.
Example:
Converting list to set
We can convert list to set and set to list back. Converting list to set removes duplicates and only unique items will be reserved.
# syntax
lst = ['item1', 'item2', 'item3', 'item4', 'item1']
st = set(lst) # {'item2', 'item4', 'item1', 'item3'}
Example:
fruits = ['banana', 'orange', 'mango', 'lemon','orange', 'banana']
fruits = set(fruits) # {'mango', 'lemon', 'banana', 'orange'}
Joining sets
We can join two using the union() or *update() method. * Union This method returns a new set
# syntax
st1 = {'item1', 'item2', 'item3', 'item4'}
st2 = {'item5', 'item6', 'item7', 'item8'}
st3 = st1.union(st2)
fruits = {'banana', 'orange', 'mango', 'lemon'}
vegetables = {'Tomato', 'Potato', 'Cabbage','Onion', 'Carrot'}
fruits.union(vegetables) # {'lemon', 'Carrot', 'Tomato', 'banana', 'mango', 'orange', 'Cabbage', 'Potato', 'Onion'}
# syntax
st1 = {'item1', 'item2', 'item3', 'item4'}
st2 = {'item5', 'item6', 'item7', 'item8'}
st1.update(st2)
fruits = {'banana', 'orange', 'mango', 'lemon'}
vegetables = {'Tomato', 'Potato', 'Cabbage','Onion', 'Carrot'}
fruits.update(vegetables)
print(fruits) # {'lemon', 'Carrot', 'Tomato', 'banana', 'mango', 'orange', 'Cabbage', 'Potato', 'Onion'}
Finding intersection items
Intersection returns a set of items which are in both the sets. See the example
# syntax
st1 = {'item1', 'item2', 'item3', 'item4'}
st2 = {'item3', 'item2'}
st1.intersection(st2) # {'item3', 'item2'}
whole_numbers = {0, 1, 2, 3, 4, 5, 6, 7, 8, 10}
even_numbers = {0, 2, 4, 6, 8, 10}
whole_numbers.intersection(even_numbers) # {0, 2, 4, 6, 8, 10}
python = {'p', 'y', 't', 'o','n'}
dragon = {'d', 'r', 'a', 'g', 'o','n'}
python.intersection(dragon) # {'o', 'n'}
Checking subset and super set
A set can be a subset or super set of other sets: * Subset: issubset() * Super set: issuperset
# syntax
st1 = {'item1', 'item2', 'item3', 'item4'}
st2 = {'item2', 'item3'}
st2.issubset(st1) # True
st1.issuperset(st2) # True
whole_numbers = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10}
even_numbers = {0, 2, 4, 6, 8, 10}
whole_numbers.issubset(even_numbers) # False, because it is super set
whole_numbers.issuperset(even_numbers) # True
python = {'p', 'y', 't', 'o','n'}
dragon = {'d', 'r', 'a', 'g', 'o','n'}
python.issubset(dragon) # False
Checking difference between two sets
It return the difference between the two sets.
# syntax
st1 = {'item1', 'item2', 'item3', 'item4'}
st2 = {'item2', 'item3'}
st2.difference(st1) # {'item1', 'item4'} => st1\st2
whole_numbers = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10}
even_numbers = {0, 2, 4, 6, 8, 10}
whole_numbers.difference(even_numbers) # {1, 3, 5, 7}
python = {'p', 'y', 't', 'o','n'}
dragon = {'d', 'r', 'a', 'g', 'o','n'}
python.difference(dragon) # {'p', 'y', 't'}
dragon.difference(python) # {'d', 'r', 'a', 'g'}
Finding Symmetric difference between two sets
It return the the symmetric difference between the two sets, it means that it return a set that contains all items from both sets, except items that are present in both set, mathematically: (A\B) U (B\A)
# syntax
st1 = {'item1', 'item2', 'item3', 'item4'}
st2 = {'item2', 'item3'}
# it mean (A\B)U(B)
st2.symmetric_difference(st1) # {'item1', 'item4'}
whole_numbers = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10}
even_numbers = {1, 2, 3, 4, 5}
whole_numbers.symmetric_difference(even_numbers) # {0, 6, 7, 8, 9, 10}
python = {'p', 'y', 't', 'o','n'}
dragon = {'d', 'r', 'a', 'g', 'o','n'}
python.symmetric_difference(dragon) # {'r', 't', 'p', 'y', 'g', 'a', 'd'}
Joining set
If two set do not have common item or items we call it disjoint set. We can check if two sets are joint or disjoint using isdisjoint() method.
# syntax
st1 = {'item1', 'item2', 'item3', 'item4'}
st2 = {'item2', 'item3'}
st2.isdisjoint(st1) # False
even_numbers = {0, 2, 4 ,6, 8}
even_numbers = {1, 3, 5, 7, 9}
even_numbers.isdisjoint(odd_numbers) # True, because no common item
python = {'p', 'y', 't', 'o','n'}
dragon = {'d', 'r', 'a', 'g', 'o','n'}
python.disjoint(dragon) # False, there is common items {'o', 'n'}
💻 Exercises: Day 7
# sets
it_companies = {'Facebook', 'Google', 'Microsoft', 'Apple', 'IBM', 'Oracle', 'Amazon'}
A = {19, 22, 24, 20, 25, 26}
B = {19, 22, 20, 25, 26, 24, 28, 27}
age = [22, 19, 24, 25, 26, 24, 25, 24]
📘 Day 8
Dictionary
A dictionary is a collection of unordered, modifiable(mutable) key value paired data type.
Creating a dictionary
To create a dictionary we use a curly bracket, {}.
# syntax
empty_dict = {}
# Dictionary with data values
dct = {'key1':'item1', 'key2':'item2', 'key3':'item3', 'key4':'item4'}
person = {
'first_name':'Asabeneh',
'last_name':'Yetayeh',
'age':250,
'country':'Finland',
'is_marred':True,
'skills':['JavaScript', 'React', 'Node', 'MongoDB', 'Python']
'address':{
'street':'Space street',
'zipcode':'02210'
}
}
The dictionary above shows that a value could be any different data type:string, boolean, list, tuple, set or a dictionary.
Dictionary Length
It checks the number of key value pairs in the dictionary.
Example:person = {
'first_name':'Asabeneh',
'last_name':'Yetayeh',
'age':250,
'country':'Finland',
'is_marred':True,
'skills':['JavaScript', 'React', 'Node', 'MongoDB', 'Python'],
'address':{
'street':'Space street',
'zipcode':'02210'
}
}
print(len(person)) # 7
Accessing a dictionary items
We can access a dictionary items by referring to its key name.
# syntax
dct = {'key1':'item1', 'key2':'item2', 'key3':'item3', 'key4':'item4'}
print(dct['key1']) # item1
print(dct['key4']) # item4
person = {
'first_name':'Asabeneh',
'last_name':'Yetayeh',
'age':250,
'country':'Finland',
'is_marred':True,
'skills':['JavaScript', 'React', 'Node', 'MongoDB', 'Python'],
'address':{
'street':'Space street',
'zipcode':'02210'
}
}
print(person['first_name']) # Asabeneh
print(person['country']) # Finland
print(person['skills']) # ['HTML','CSS','JavaScript', 'React', 'Node', 'MongoDB', 'Python']
print(person['city']) # Error
person = {
'first_name':'Asabeneh',
'last_name':'Yetayeh',
'age':250,
'country':'Finland',
'is_marred':True,
'skills':['JavaScript', 'React', 'Node', 'MongoDB', 'Python'],
'address':{
'street':'Space street',
'zipcode':'02210'
}
}
print(person.get('first_name')) # Asabeneh
print(person.get('country')) # Finland
print(person.get('skills')) #['HTML','CSS','JavaScript', 'React', 'Node', 'MongoDB', 'Python']
print(person.get('city')) # None
Adding Item to a dictionary
We can add new key and value pair to a dictionary
# syntax
dct = {'key1':'item1', 'key2':'item2', 'key3':'item3', 'key4':'item4'}
dct['key5'] = 'item5'
person = {
'first_name':'Asabeneh',
'last_name':'Yetayeh',
'age':250,
'country':'Finland',
'is_marred':True,
'skills':['JavaScript', 'React', 'Node', 'MongoDB', 'Python'],
'address':{
'street':'Space street',
'zipcode':'02210'
}
}
person['job_title'] = 'Instructor'
person['skills'].append('HTML')
print(person)
Modifying Item in a dictionary
We can add modify item in a dictionary
# syntax
dct = {'key1':'item1', 'key2':'item2', 'key3':'item3', 'key4':'item4'}
dct['key1'] = 'item-one'
person = {
'first_name':'Asabeneh',
'last_name':'Yetayeh',
'age':250,
'country':'Finland',
'is_marred':True,
'skills':['JavaScript', 'React', 'Node', 'MongoDB', 'Python'],
'address':{
'street':'Space street',
'zipcode':'02210'
}
}
person['first_name'] = 'Eyob'
person['age']
Checking a key in a dictionary
We use the in operator to check if a key exist in a dictionary
# syntax
dct = {'key1':'item1', 'key2':'item2', 'key3':'item3', 'key4':'item4'}
print('key2' in dct) # True
print('key5' in dct) # False
Removing key items from dictionary
- pop(key): removes the item with the specified key name:
- popitem(): remove the last time
- del: removes the item with the specified key name
# syntax
dct = {'key1':'item1', 'key2':'item2', 'key3':'item3', 'key4':'item4'}
dct.pop('key1') # the first key pair removed
dct = {'key1':'item1', 'key2':'item2', 'key3':'item3', 'key4':'item4'}
dct.popitem() # remove the last item
del dct['key2'] # remove key 2 item
Example:
person = {
'first_name':'Asabeneh',
'last_name':'Yetayeh',
'age':250,
'country':'Finland',
'is_marred':True,
'skills':['JavaScript', 'React', 'Node', 'MongoDB', 'Python'],
'address':{
'street':'Space street',
'zipcode':'02210'
}
}
person.pop('first_name') # Remove the firstname item
person.popitem() # Remove the lastname item
del person['is_married'] # Remove the is_married item
Changing dictionary to list items
The items() method change a dictionary to list of tuples.
# syntax
dct = {'key1':'item1', 'key2':'item2', 'key3':'item3', 'key4':'item4'}
print(dct.items()) # dict_items([('key1', 'item1'), ('key2', 'item2'), ('key3', 'item3'), ('key4', 'item4')])
Clearing dictionary list items
If we don't want the items in a dictionary we can clear them using clear() methods
# syntax
dct = {'key1':'item1', 'key2':'item2', 'key3':'item3', 'key4':'item4'}
print(dct.clear()) # {}
Deleting dictionary
If we do not use the dictionary we can delete it completely
Copy a dictionary
We copy a dictionary using a copy() method. Using copy we can avoid mutation of the original dictionary.
# syntax
dct = {'key1':'item1', 'key2':'item2', 'key3':'item3', 'key4':'item4'}
dct_copy = dct.copy() # {'key1':'item1', 'key2':'item2', 'key3':'item3', 'key4':'item4'}
Getting dictionary keys as list
The keys() method gives us all the keys of a a dictionary as a list.
# syntax
dct = {'key1':'item1', 'key2':'item2', 'key3':'item3', 'key4':'item4'}
keys = dct.keys()
print(keys) # dict_keys(['key1', 'key2', 'key3', 'key4'])
Getting dictionary values as list
The values method gives us all the values of a a dictionary as a list.
# syntax
dct = {'key1':'item1', 'key2':'item2', 'key3':'item3', 'key4':'item4'}
values = dct.values()
print(values) # dict_values(['item1', 'item2', 'item3', 'item4'])
💻 Exercises: Day 8
- Create a an empty dictionary called dog
- Add name, color, breed, legs, age to the dog, dictionary
- Create a student dictionary and add first_name, last_name, gender, age, marital status, skills, country, city and address as key for the dictionary
- Get the length of student dictionary
- Get the value of skills and check the data type, it should be list
- Modify the skills value by adding one or two skills
- Get the dictionary keys as list
- Get the dictionary values as list
- Change the dictionary to a list of tuples using *items() method
- Delete one of the item in the dictionary
- Delete the dictionary completely
📘 Day 9
Conditionals
By default , statements in python script executed sequentially from top to bottom. If the processing logic require so, the sequential flow of execution can be altered in two way: * Conditional execution: a block of one or more statements will be executed if a certain expression is true * Repetitive execution: a block of one or more statements will be repetitively executed as long as a certain expression is true. In this section, we will cover if, else , elif statements. The comparison and logical operator we learned in the previous sections will be useful here.
If condition
In python and other programming languages the key word if use to check if a condition is true and to execute the block code. Remember the indentation after the colon.
Example: As you can see in the above condition, 3 is greater than 0 and it is a positive number. The condition was true and the block code was executed. However, if the condition is false, we do not see a result. In order to see the result of the falsy condition, we should have another block, which is going to be else.If Else
If condition is true the first block will be executed, if not the else condition will run.
# syntax
if condition:
this part of code run for truthy condition
else:
this part of code run for false condition
If elif else
On our daily life, we make decision on daily basis. We make decision not by checking one or two conditions instead multiple conditions. As similar to life, programming is also full conditions. We use elif when we have multiple conditions.
Example:a = 0
if a > 0:
print('A is a positive number')
elif a < 0:
print('A is a negative number')
else:
print('A is zero')
Short Hand
Example:Nested condition
Condition can be nested
Example:a = 0
if a > 0:
if a % 2 == 0:
print('A is positive even integer')
else:
print('A positive number')
elif a == 0:
print('Zero')
else:
print('A negative number')
If condition and and logical operator
Example:a = 0
if a > 0 and a % 2 == 0:
print('A is even positive integer')
elif a > 0 and a % 2 !== 0:
print('A is positive integer')
elif a == 0:
print('Zero')
else:
print('A negative number')
If and or logical operator
Example:a = 0
if a > 0 or % 2 == 0:
print('A is positive integer')
elif a == 0:
print('Zero')
else:
print('A negative number')
💻 Exercises: Day 9
- Get user input using input(“Enter your age:”). If user is 18 or older , give feedback:You are old enough to drive but if not 18 give feedback to wait for the years he supposed to wait for. Output:
- Compare the values of my_age and your_age using if … else. Based on the comparison print who is older (me or you). Use input(“Enter your age:”) to get the age as input. Output:
- Get two numbers from user using, input prompt. If a is greater than b return a is greater than b,if a is less b return a lesson b, else a is equal to b. Output:
- Write a code which give grade to students according to theirs scores:
- Check if the season is Autumn, Winter, Spring or Summer. If the user input is: September, October or November, the season is Autumn. December, January or February, the season is Winter. March, April or May, the season is Spring June, July or August, the season is Summer
- The following list contains some fruits: If a fruit doesn't exist in the list add the fruit in the list and print the modified list but if the fruit exists print('A fruit already exist in the list')
- Here we have a person dictionary.
- Check if the person dictionary has skills, if it has skills key check print out the middle skill in the skills list.
- Check if the person dictionary has skills, if it has skills key check if the person has 'Python' skill and print the skill.
- If a person skills has only JavaScript and React, print('He is a front end developer'), if the person skills has Node, Python, MongoDB, print ('He is a backend developer'), if the person skills has React, Node and MongoDB, Print('He is a fullstack developer'), else print('unknown title')
- If the person is married and if he lives in Finland, print the following: << Part 2 | Part 4 >>