2+2

4

5/0

---------------------------------------------------------------------------
ZeroDivisionError                         Traceback (most recent call last)
Cell In[3], line 1
----> 1 5/0

ZeroDivisionError: division by zero

number = 42

text = "Hello, World"

notnumber = "42"

print(text)

Hello, World

print(number + 58)

100

print(number + notnumber)

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
Cell In[8], line 1
----> 1 print(number + notnumber)

TypeError: unsupported operand type(s) for +: 'int' and 'str'

print(7 + "cat")

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
Cell In[9], line 1
----> 1 print(7 + "cat")

TypeError: unsupported operand type(s) for +: 'int' and 'str'

print(notnumber)
print(number)

42
42

type(notnumber)

str

newnumber = int(notnumber)
print(newnumber)
type(newnumber)

42

int

print(number+newnumber)

84

myfloat = float(newnumber)+0.5
print(myfloat)

42.5

my_list = [1, 2, 3, "four"]
print(my_list)

[1, 2, 3, 'four']

obj0 = 12
obj1 = "cat"
obj2 = ["a", "b", "c"]
my_list1 = [obj0, obj1, obj2]
print(my_list1)

[12, 'cat', ['a', 'b', 'c']]

my_list1.append("dog")
print(my_list1)

[12, 'cat', ['a', 'b', 'c'], 'dog']

my_list2 = ["cat", "dog", "parrot"]
print(my_list2[0])
print(my_list2[1])
print(my_list2[2])
print(my_list2[3]) #there's nothing here!

cat
dog
parrot

---------------------------------------------------------------------------
IndexError                                Traceback (most recent call last)
Cell In[18], line 5
      1 my_list2 = ["cat", "dog", "parrot"]
      2 print(my_list2[0])
      3 print(my_list2[1])
      4 print(my_list2[2])
----> 5 print(my_list2[3]) #there's nothing here!

IndexError: list index out of range

my_list1[0:2]

[12, 'cat']

print(len(my_list1))

4

my_str = "The quick brown fox jumps over the lazy dog."
print(my_str[4])
print(my_str[4:9]) #4:9 indicates characters 4-8

q
quick

print(my_str[-4:])
print(my_str[:4])

dog.
The

["home", "away"][0][0:3]

'hom'

["home", "away"][0]

'home'

class_dict = {"course":"Python II", "location":"Davis Library", "time":"4pm"}
type(class_dict)

dict

print(class_dict["location"])

Davis Library

print(class_dict.keys())

dict_keys(['course', 'location', 'time'])

num=5
num<3

False

letter="a"
letter in ["a","b","c"]

True

num = 5
if num > 4:
    print("This number is greater than four")

This number is greater than four

num = 3
if num > 4:
    print("This number is greater than than four")
else:
    print("This number is less than or equal to four")

This number is less than or equal to four

num = 8
if num < 3:
    print("This number is less than three")
elif num < 10:
    print("This number is greater than or equal to three and less than ten")
else:
    print("This number is greater than or equal to ten")

This number is greater than or equal to three and less than ten

sales = [5, 2, 7, 9, 3]
total_sales = 0
total_sales = total_sales + sales[0]
total_sales = total_sales + sales[1]
total_sales = total_sales + sales[2]
total_sales = total_sales + sales[3]
total_sales = total_sales + sales[4]
print(total_sales)

26

my_nums = list(range(6))
print(list(range(6)))
for n in my_nums:
    print(n)

[0, 1, 2, 3, 4, 5]
0
1
2
3
4
5

#Nesting loops - indentation is key!
listOfWords = ["blue", "yellow", "red", "green"]
newList = [] #initialize an empty list

for color in listOfWords:
    numLetters = 0 #resets to zero each time the loop runs
    for letter in color:
        numLetters += 1
    temporaryList = [color, numLetters]
    newList.append(temporaryList)
    
print(newList)

[['blue', 4], ['yellow', 6], ['red', 3], ['green', 5]]

for number in range(10):
    if number % 2 == 0: 
    # % denotes the modulo operation - the result is the remainder after dividing by 2 
    # (i.e. 6%2 = 0, but 5%2 = 1)
        print(number)

scores=[95, 90, 66, 83, 71, 78, 93, 81, 87, 81]
grades=[]
for score in scores:
    if score >= 90:
        grade = "A"
    elif score >= 80:
        grade = "B"
    elif score >= 70 and score < 80:
        grade = "C"
    elif score >= 60 and score < 70:
        grade = "D"
    else:
        grade = "F"
    grades.append([score, grade])       
print(grades)

[[95, 'A'], [90, 'A'], [66, 'D'], [83, 'B'], [71, 'C'], [78, 'C'], [93, 'A'], [81, 'B'], [87, 'B'], [81, 'B']]

squares=[]
for n in range(1, 16):
    squares.append(n**2)
print(squares)

[1, 4, 9, 16, 25, 36, 49, 64, 81, 100, 121, 144, 169, 196, 225]

squares=[x**2 for x in range(1, 16)]
print(squares)

[1, 4, 9, 16, 25, 36, 49, 64, 81, 100, 121, 144, 169, 196, 225]

squaresdict={k:k**2 for k in range(1, 16)}
print(squaresdict)

{1: 1, 2: 4, 3: 9, 4: 16, 5: 25, 6: 36, 7: 49, 8: 64, 9: 81, 10: 100, 11: 121, 12: 144, 13: 169, 14: 196, 15: 225}

sentence="the quick brown fox jumped over the lazy dog"
sentence=sentence.split(" ") #splits the string into a list with each space
print(sentence)
print([w for w in sentence if len(w)>4])

['the', 'quick', 'brown', 'fox', 'jumped', 'over', 'the', 'lazy', 'dog']
['quick', 'brown', 'jumped']

random_words=["statement", "toy", "cars", "shoes", "ear", "busy", 
              "magnificent", "brainy", "healthy", "narrow", "join", 
              "decay", "dashing", "river", "gather", "stop", "satisfying", 
              "holistic", "reply", "steady", "event", "house", "amused", 
              "soak", "increase"]

vowels=["a", "e", "i", "o", "u", "y"]

output=[]

for word in random_words:
    count = 0
    for char in word:
        if char in vowels:
            count = count + 1
    if count >= 3:
        output.append([word, count])

#1. Get or define the list my_numbers
my_numbers=list(range(100))

#2. Create an empty list for the new all-odd numbers, called my_numbers2.

#3. Use a loop to iterate through the list of numbers

    #3a. For a given number check to see if it is even.
    
    #3b. If the number is even, add 1.
    
    #3c. Append the resulting number to the my_numbers2 list.

user_ages=["34", "27", "54", "19", "giraffe", "15", "83", "61", "43", "91", "sixteen"]

ages = []
problems = []

for age in user_ages:
    try:
        a = int(age)
        ages.append(a)
    except:
        problems.append(age)
        
print(ages)
print(problems)

[34, 27, 54, 19, 15, 83, 61, 43, 91]
['giraffe', 'sixteen']

def mean(number_list):
    s = sum(number_list)
    n = len(number_list)
    m = s/n
    return m

numbers=list(range(1, 51))
print(mean(numbers))

25.5

Type	Example	Description
`int`	1, 2, 3	Integers (whole numbers)
`float`	1.5, 2.72, 3.14	Floating point numbers (decimals)
`str`	"cat", "dog", "car"	String, character, or text values
`list`	[1, 2, 3], ["cat", "dog"], [1, [2, 3]]	One or more objects indexed by order
`dict`	{"first_name":"John", "last_name":"Doe"}	One or more objects indexed by key values

Python: Session 1¶

Why Python?¶

Use Cases¶

Scripting¶

Natural Language Processing¶

Data Science¶

Others¶

Python vs. R¶

Warning!

Getting Started¶

IDEs¶

Create project folder¶

Set up uv Project¶

Open Jupyter Notebook file¶

You're ready!¶

Entering code¶

Data Types and Variables¶

Strings and Numbers¶

Getting help with functions¶

Lists¶

Indexing¶

Extra: Indexing beyond lists¶

Dictionaries¶

Review: Data Types¶

Flow Control¶

Conditions and Booleans¶

Conditional Statements¶

For Loops¶

Extra: Nested Loops¶

For Loops with Conditionals¶

Comprehensions¶

Review¶