sports = ["football", "hockey", "baseball", "basketball"]
# change the value "soccer" to "hockey"
print (sports)
sports = ["football", "soccer", "golf", "basketball"]
# add "golf" as the 3rd element in the list
print (sports)
Iterations
Iteration is the repetition of a process or utterance applied to the result or taken from a previous statement. There's a lot of types of iteration though, what to use? How do we apply iteration to lists?
Some methods include using a "for loop", using a "for loop and range()", using a "while loop", and using comprehension
Lists, tuples, dictionaries, and sets are iterable objects. They are the 'containers' that store the data to iterate.
Each of these containers are able to iterate with the iter() command.
There are 2 types of iteration:definite and indefinite. Definite iteration clarifies how many times the loop is going to run, while indefinite specifies a condition that must be met.
When an object is iterable it can be used in an iteration.
When passed through the function iter() it returns an iterator.
Strings, lists, dictionaries, sets and tuples are all examples of iterable objects.
a = ['alpha', 'bravo', 'charlie']
itr = iter(a)
print(next(itr))
print(next(itr))
print(next(itr))
list = ["Alpha", "Bravo", "Charlie", "Delta", "Echo", "Foxtrot", "Golf", "Hotel", "India", "Juliett", "Kilo", "Lima", "Mike", "November", "Oscar", "Papa", "Quebec", "Romeo", "Sierra", "Tango", "Uniform", "Victor", "Whiskey", "X-ray", "Yankee", "Zulu"]
# using a for loop
for i in list:
#for item in the list, print the item
print(i)
list = ["Alpha", "Bravo", "Charlie", "Delta", "Echo", "Foxtrot", "Golf", "Hotel", "India", "Juliett", "Kilo", "Lima", "Mike", "November", "Oscar", "Papa", "Quebec", "Romeo", "Sierra", "Tango", "Uniform", "Victor", "Whiskey", "X-ray", "Yankee", "Zulu"]
# Taking the length of the list
lengthList = len(list)
# Iteration using the amount of items in the list
for i in range(lengthList):
print(list[i])
list = ["Alpha", "Bravo", "Charlie", "Delta", "Echo", "Foxtrot", "Golf", "Hotel", "India", "Juliett", "Kilo", "Lima", "Mike", "November", "Oscar", "Papa", "Quebec", "Romeo", "Sierra", "Tango", "Uniform", "Victor", "Whiskey", "X-ray", "Yankee", "Zulu"]
# Once again, taking the length of the list
lengthList = len(list)
# Setting the variable we are going to use as 0
i=0
# Iteration using the while loop
# Argument saying WHILE a certain variable is a certain condition, the code should run
while i < lengthList:
print(list[i])
i += 1
x = range(5)
for n in x:
print(n)
2D Iterations
A 2D array is simply just a list of lists. The example below is technically correct but conventially 2D arrays are written like below. This is because 2D arrays are meant to be read in 2 dimensions (hence the name). Writing them like below makes them easier to visualize and understand.
keypad = [[1, 2, 3], [4, 5, 6], [7, 8, 9], [" ", 0, " "]]
Conventially 2D arrays are written like below. This is because 2D arrays are meant to be read in 2 dimensions (hence the name). Writing them like below makes them easier to visualize and understand.
keypad = [[1, 2, 3],
[4, 5, 6],
[7, 8, 9],
[" ", 0, " "]]
def print_matrix1(matrix):
for i in range(len(matrix)):
for j in range(len(matrix[i])):
print(matrix[i][j], end=" ")
print()
Else, elif, and break For when 1 statement isn't enough
Else:when the condition does not meet, do statement()- Elif: when the condition does not meet, but meets another condition, do statement() Break: stop the loop HW Iteration Use the list below to turn the first letter of any word (using input()) into its respective NATO phonetic alphabet word
Ex:
list ->
lima india sierra tango
- check TABLe
Lists are just one of four collection data types in Python Tuple: collection that is ordered, unchangeable, allows duplicates Set: collection that is unordered, unchangeable, doesn't allow duplicates
Dictionary: collection that is ordered, changeable, doesn't allow duplicates Terms
Index: a term used to sort data in order to reference to an element in a list (allows for duplicates) Elements: the values in the list assigned to an index
print("Raw matrix (list of lists): ")
print(keypad)
print("Matrix printed using nested for loop iteration:")
print_matrix1(keypad)
print()
def print_matrix2(matrix):
for row in matrix:
for col in row:
print(col, end=" ")
print()
keypad = [[1, 2, 3],
[4, 5, 6],
[7, 8, 9],
[" ", 0, " "]]
print_matrix2(keypad)
fruit = ["apples", "bananas", "grapes"]
print(fruit)
print(*fruit)
def print_matrix3(matrix):
for row in matrix:
print(*row)
print_matrix3(keypad)
def print_matrix4(matrix):
matrix_iter = iter(matrix)
for i in range(len(matrix)):
inner_matrix_iter = iter(next(matrix_iter))
for j in matrix[i]:
print(str(next(inner_matrix_iter)), end=" ")
print()
print_matrix4(keypad)
keyboard = [["`", 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, "-", "="],
["Q", "W", "E", "R", "T", "Y", "U", "I", "O", "P", "[", "]"],
["A", "S", "D", "F", "G", "H", "J", "K", "L", ";", "'"],
["Z", "X", "C", "V", "B", "N", "M", ",", ".", "/"]]
output = "DECEMBER16"
for char in output: #each item in the output is a character
for row in keyboard: #each item in the keyboard is a row
for key in row: #each item in the row is a key
if str(key) == char: #if the key matches each character in output
print(key, end='')
break #ends the loop. back to first loop
keyboard = [["`", 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, "-", "="],
["Q", "W", "E", "R", "T", "Y", "U", "I", "O", "P", "[", "]"],
["A", "S", "D", "F", "G", "H", "J", "K", "L", ";", "'"],
["Z", "X", "C", "V", "B", "N", "M", ",", ".", "/"]]
output = "DECEMBER16"
for row in keyboard:
for key in row:
if str(key) in output:
print(key, end='')
else:
print(" ", end='')
print("\n")