Keywords

(Def) Predefined words, that has specific meaning and can’t be used as constants, variables or other identifier names.

import keyword
keyword.iskeyword("?")

False

keyword.kwlist

['False',
 'None',
 'True',
 'and',
 'as',
 'assert',
 'async',
 'await',
 'break',
 'class',
 'continue',
 'def',
 'del',
 'elif',
 'else',
 'except',
 'finally',
 'for',
 'from',
 'global',
 'if',
 'import',
 'in',
 'is',
 'lambda',
 'nonlocal',
 'not',
 'or',
 'pass',
 'raise',
 'return',
 'try',
 'while',
 'with',
 'yield']

Dynamic Typing

(Def) One can reassign the variable to different data type.

city_schools = 2

city_schools = ["public", "private"]

type(city_schools)

list

type(2)

int

Data Types & Structures

1. Strings

Collection of characters

name = "Jagiellonian University"

len(name)

23

name[10]

'a'

name[3:]

'iellonian University'

name[:3]

'Jag'

name[-3]

'i'

name[-2:]

'ty'

# name[0] = "L" #Can you think of a way to do this?

name + " is oldest university in Krakow."

'Jagiellonian University is oldest university in Krakow.'

name_course = "This is {initial} course for beginners".format(initial="Python")
name_course

'This is Python course for beginners'

Marks = "In Graduation I got %5.2f percent marks but in masters I got %6.3f percent marks:"%(73.778,84.54432)
Marks

'In Graduation I got 73.78 percent marks but in masters I got 84.544 percent marks:'

Marks.split()

['In',
 'Graduation',
 'I',
 'got',
 '73.78',
 'percent',
 'marks',
 'but',
 'in',
 'masters',
 'I',
 'got',
 '84.544',
 'percent',
 'marks:']

Marks.split("I")

['',
 'n Graduation ',
 ' got 73.78 percent marks but in masters ',
 ' got 84.544 percent marks:']

Marks.upper()

'IN GRADUATION I GOT 73.78 PERCENT MARKS BUT IN MASTERS I GOT 84.544 PERCENT MARKS:'

Marks.lower()

'in graduation i got 73.78 percent marks but in masters i got 84.544 percent marks:'

Marks.find("T") #-1 when not found

-1

Marks.find("I", 0, 11)

0

Marks.replace("I", "Y")

'Yn Graduation Y got 73.78 percent marks but in masters Y got 84.544 percent marks:'

2. Lists

Lists are mutable.

l = ["Jagiellonian", "Bio", 1354, "Bio", "Phy", "Che"]

len(l)

6

l[-1]

'Che'

l[3]

'Bio'

l + ["Hello"]

['Jagiellonian', 'Bio', 1354, 'Bio', 'Phy', 'Che', 'Hello']

l

['Jagiellonian', 'Bio', 1354, 'Bio', 'Phy', 'Che']

l += ["Hello"]

l

['Jagiellonian', 'Bio', 1354, 'Bio', 'Phy', 'Che', 'Hello']

l*5

['Jagiellonian',
 'Bio',
 1354,
 'Bio',
 'Phy',
 'Che',
 'Hello',
 'Jagiellonian',
 'Bio',
 1354,
 'Bio',
 'Phy',
 'Che',
 'Hello',
 'Jagiellonian',
 'Bio',
 1354,
 'Bio',
 'Phy',
 'Che',
 'Hello',
 'Jagiellonian',
 'Bio',
 1354,
 'Bio',
 'Phy',
 'Che',
 'Hello',
 'Jagiellonian',
 'Bio',
 1354,
 'Bio',
 'Phy',
 'Che',
 'Hello']

# l.sort() #Not for list with strings

l.reverse()

l

['Hello', 'Che', 'Phy', 'Bio', 1354, 'Bio', 'Jagiellonian']

l.index("Che")

1

l.extend([1,2,3])

l

['Hello', 'Che', 'Phy', 'Bio', 1354, 'Bio', 'Jagiellonian', 1, 2, 3]

l.clear()

l

[]

l = [3,1,4,1,5,9,2,6,5,3]

l.insert(2,7)

l

[3, 1, 7, 4, 1, 5, 9, 2, 6, 5, 3]

lc = l
lc[-1] = 3
lc,l

([3, 1, 7, 4, 1, 5, 9, 2, 6, 5, 3], [3, 1, 7, 4, 1, 5, 9, 2, 6, 5, 3])

lc = l.copy()

lc

[3, 1, 7, 4, 1, 5, 9, 2, 6, 5, 3]

lc[-1]=2

lc,l

([3, 1, 7, 4, 1, 5, 9, 2, 6, 5, 2], [3, 1, 7, 4, 1, 5, 9, 2, 6, 5, 3])

l.remove(3) #Removes the first occurence of 3

l

[1, 7, 4, 1, 5, 9, 2, 6, 5, 3]

l.pop(3) #Removes the element at 3rd index

1

l.append(2)

3. Tuples

Tuples are immutable.

my_first_tuple = ("apple", "mango", "banana")

my_first_tuple = ("apple", "mango", "banana", "mango")

my_first_tuple

('apple', 'mango', 'banana', 'mango')

my_first_tuple = ("apple", "mango", 32)

my_first_tuple = ("apple",)

fruits_tuple = ('apple', 'banana', 'mango')

print("First element:", fruits_tuple[0])
print("Last element:", fruits_tuple[-1])

duplicate_tuple = ('apple', 'mango', 'banana', 'mango', 'apple')
print("Tuple with duplicates:", duplicate_tuple)

# Tuple immutability (this would raise an error if uncommented)
# fruits_tuple[1] = 'orange'

print("Length of duplicate tuple:", len(duplicate_tuple))

banana_index = duplicate_tuple.index('banana')
print("Index of 'banana':", banana_index)

apple_count = duplicate_tuple.count('apple')
print("Number of times 'apple' appears:", apple_count)

final_tuple = fruits_tuple + duplicate_tuple
print("Concatenated tuple:", final_tuple)

my_tuple = (10, 20, 30)
a, b, c = my_tuple
print("Unpacked values:", a, b, c)

my_tuple = (10, 20, 30)
print(20 in my_tuple)
print(40 not in my_tuple)

my_tuple = (1, 2)
print(my_tuple * 3)

my_tuple = (10, 20, 30)
print("Minimum value:", min(my_tuple))
print("Maximum value:", max(my_tuple))

First element: apple
Last element: mango
Tuple with duplicates: ('apple', 'mango', 'banana', 'mango', 'apple')
Length of duplicate tuple: 5
Index of 'banana': 2
Number of times 'apple' appears: 2
Concatenated tuple: ('apple', 'banana', 'mango', 'apple', 'mango', 'banana', 'mango', 'apple')
Unpacked values: 10 20 30
True
True
(1, 2, 1, 2, 1, 2)
Minimum value: 10
Maximum value: 30

4. Dictionary

Key-value pairs

my_first_dict = {
    'Best_City': 'Krakow',
    'Best_University': 'Jagiellonian',
    'Best_place': 'market_square',
    'Best_food': 'spicy',
    'Best_sport': 'volleyball',
    'Year': 2022
}

print(my_first_dict)

print(my_first_dict['Best_place'])
print(my_first_dict['Best_food'])

{'Best_City': 'Krakow', 'Best_University': 'Jagiellonian', 'Best_place': 'market_square', 'Best_food': 'spicy', 'Best_sport': 'volleyball', 'Year': 2022}
market_square
spicy

my_first_dict = {
    'Best_City': ['Krakow', 'Warsaw', 'Lublin'],
    'Best_University': 'Jagiellonian'
}

print(my_first_dict['Best_City'][2])   # Output: 'Lublin'

my_first_dict['Best_habit'] = 'reading'
my_first_dict['year'] = 2022

print(my_first_dict['year'] - 5)       # Output: 2017

Lublin
2017

fruit_inventory = {'apple': 2, 'banana': 5, 'mango': 10}

print("Keys:",fruit_inventory.keys())
print("Values:",fruit_inventory.values())

mango_quantity = fruit_inventory.get('mango')

fruit_inventory['orange'] = 7
fruit_inventory['apple'] = 4
print("Updated inventory:",fruit_inventory)

fruit_inventory.pop('banana')

Keys: dict_keys(['apple', 'banana', 'mango'])
Values: dict_values([2, 5, 10])
Updated inventory: {'apple': 4, 'banana': 5, 'mango': 10, 'orange': 7}

5

Decision Making

Should I go to class or not?

x = 10
if x>10:
  print("Number is Greater")

if x>10:
  print("Number is Greater")
else:
  print("Number is Smaller")

Number is Smaller

if x>10:
  print("Number is Greater")
elif x==10:
  print("Number is smaller")
else:
  print("Number is smaller")

Number is smaller

Looping in Python

Executing same action several times

for x in range(1,11):
  print(x)

1
2
3
4
5
6
7
8
9
10

#Q: Print only odd/even numbers?

for letter in "coffee":
  print(letter*10)

cccccccccc
oooooooooo
ffffffffff
ffffffffff
eeeeeeeeee
eeeeeeeeee