Week 1-3

String Slicing: How would you slice the string (defined as ‘s’) ‘Hello World’ to get ‘Hello’ and then ‘World’ and then ‘Hello World’

s = "Hello World"
print(s[0:5]) or print(s[:5]) # - ‘Hello’
print(s[6:11]) or print(s[6:]) # - ‘World’
print(s[:]) # - ‘Hello World’

Using string slicing, how would you change the string (defined as ‘s’) ‘Hello, World!’ to print ‘Yello, World!’

s = "Hello, World!"
s_new = "Y" + s[1:]

What would be the outcome of these lines of code:

string = ‘hello’
t = tuple(hello)
print(t)

(‘h’, ‘e’, ‘l’, ‘l’, ‘o’)

How to define a tuple called ‘t’ with one single character: ‘a’

t = tuple('a',)

What are the symbols for quotient (DIV) and remainder (MOD) in python?

Quotient: ‘//’
Remainder: ‘%’

How do you use the ‘math’ module in python? (Allows ‘radians’ ‘sqrt’ etc. to be used)

import math

At the top of the code

Write a for statement to print: word = ‘Hello’ 1000 times

word = "Hello"
for i in range(1000):
    print(word)

Write a while statement to print: word = “Hello” 1000 times

word ="Hello"
i = 0
while i < 1000:
    print(word)
    i+=1

In the function: range(start, stop, step) - what do each of the parameters refer to?

start → the starting value (inclusive)
stop → the ending value (exclusive)
step → what to increment by (usually 1)

How do you reverse:
sentence = ‘Hello, World!’

sentence = "Hello, World"
sentence_reversed = reversed(sentence)

Using the break statement, write code that takes user input until they write ‘done’

while True: 
    line = input('> ') 
    if line == 'done': 
        break 
    print('You wrote:', line)

print('Done!') 

Write code, using the continue statement, that executes the odd numbers from:
numbers = [1,2,3,4,5]

numbers = [1, 2, 3, 4, 5]

for num in numbers:
    if num % 2 == 0:
        continue # Skips the print() if its divisible by 2
    print(num)

Write code that prints a 2 × 3 matrix from the 2 dimensional list:
matrix = [[1, 2, 3],
[4, 5, 6]]

matrix = [[1, 2, 3],
          [4, 5, 6]]

for row in matrix:
    for element in row:
        print(element, end=" ") # The 'end' seperates each by a white space
    print()  # Start a new line for the matrix

Use the string method: ‘find’ to find where ‘na’ appears in the string
‘word = banana’

word = "banana"
index_1 = word.find("na")
index_2 = word.find("na", 3) #Tells to start at index 3

print(index_1, index_2)

Would print ‘2’ and ‘4’ because that is where the index for both are

Write code using the ‘in’ operator, that locates the letters that are found in 2 words passed into the function ‘in_both’

def in_both(word1, word2): 
    for letter in word1: 
        if letter in word2: 
            print(letter) 

Using the f-string and the variables:
name = Ruby
age = 18
Write a line of code that returns the name and age of the person.

print(f"Hello, my name is {name} and my age is {age}")

Write a line of code that concatenates the two lists:
[1, 2, 3] and [4, 5, 6]

lst_one = [1,2,3]
lst_two = [4,5,6]

new_lst = lst_one + lst_two

print(new_lst)

Would return [1,2,3,4,5,6]

What does this line of code do?
list(zip('abc', [1,2,3]))

Creates 3 tuples using the ‘zip’ function, using each value in the string and list and sets each of the tuple pairs as values of a list. Would return

[(a,1),(b,2),(c,3)]

Write code that removes the white spaces from a sentence (using user input).

sentence = input("Enter a sentence: ")
output = ""
for letter in sentence:
    if letter != " ":
        output += letter
        
print(output)

Write code that takes an input of a series of numbers (seperated by a white space, and as a string) and puts them into a list

numbers = input("Enter a series of numbers: ")
nums = numbers.split()
print(nums)

Write a function that takes a list of numbers as a string and outputs them seperated by a white space

def to_nums(list):
    string = " ".join(list)
    print(string)
    
print(to_nums(["1", "2", "3", "4"]))