2-3.3 Intro Python¶
The Power of List Iteration¶
- for in:
forloop usingin - for range:
for range(start,stop,step) - more list methods:
.extend(),+, .reverse(), .sort() - strings to lists,
.split(), and list to strings,.join()
> Student will be able to
- Iterate through Lists using
forwithin - Use
for range()in looping operations - Use list methods
.extend(),+, .reverse(), .sort() - convert between lists and strings using
.split()and.join()
¶
Concepts
Combine Lists¶
+ list addition¶
.extend() list method¶
combine lists with + and .extend()¶
visited_cities = ["New York", "Shanghai", "Munich", "Toyko", "Dubai", "Mexico City", "São Paulo", "Hyderabad"]
wish_cities = ["Reykjavík", "Moscow", "Beijing", "Lamu"]
# combine in a new list
all_cities = visited_cities + wish_cities
# add a list to an existing list
visitied_cities.extend(wish_cities)
¶
Examples
In [1]:
# [ ] review and run example
visited_cities = ["New York", "Shanghai", "Munich", "Toyko", "Dubai", "Mexico City", "São Paulo", "Hyderabad"]
wish_cities = ["Reykjavík", "Moscow", "Beijing", "Lamu"]
# .extend()
# extending visited_cities list (IN PLACE) by concatenating wish_cities
visited_cities.extend(wish_cities)
print("ALL CITIES",visited_cities)
In [2]:
# [ ] review and run example
visited_cities = ["New York", "Shanghai", "Munich", "Toyko", "Dubai", "Mexico City", "São Paulo", "Hyderabad"]
wish_cities = ["Reykjavík", "Moscow", "Beijing", "Lamu"]
# (+) Addition operator for lists creates a (NEW) combined List
all_cities = visited_cities + wish_cities
print("ALL CITIES")
for city in all_cities:
print(city)
In [3]:
# [ ] review and run example
team_a = [0,2,2,2,4,4,4,5,6,6,6]
team_b = [0,0,0,1,1,2,3,3,3,6,8]
print("Team A:", team_a, "\nTeam B:",team_b)
# (+) Addition operator
team_totals = team_a + team_b
print("Team Totals", team_totals)
In [6]:
# [ ] review and run example after running cell above
# .extend()
team_a.extend(team_b)
print("Team_a extended", team_a)
# what happens if you keep running this cell?
In [7]:
# [ ] extend the list common_birds with list birds_seen which you must create
common_birds = ["chicken", "blue jay", "crow", "pigeon"]
#Answer:
birds_seen = ['Parrot','Eagle','Falcon']
common_birds.extend(birds_seen)
print('extended common_birds = ', common_birds)
In [8]:
# [ ] Create 2 lists zero_nine and ten_onehundred that contain 1-9, and 10 - 100 by 10's.
# [ ] use list addition to concatenate the lists into all_num and print
#Answer:
zero_nine = list(range(0,10))
ten_onehundred = list(range(10,101,10))
all_num = zero_nine + ten_onehundred
print('All Numbers = ',all_num)
¶
Examples
In [9]:
# [ ] review and run example
cities_1 = ["Dubai", "Mexico City", "São Paulo", "Hyderabad"]
print("regular", cities_1)
cities_1.reverse()
print("reversed", cities_1)
In [10]:
# [ ] review and run example
all_num = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100]
print("regular list",all_num, "\n")
all_num.reverse()
print("reverse list",all_num, "\n")
num_len = len(all_num)
print("Three Multiple")
for num in all_num:
if num/3 == int(num/3):
print(num)
else:
pass
In [11]:
# [ ] review and run example
# create a list of numbers by casting a range
count_list = list(range(21))
print("before list", count_list)
# and reverse
count_list.reverse()
print("after list", count_list)
In [12]:
# [ ] create and print a list of multiples of 5 from 5 to 100
# { ] reverse the list and print
#Answer:
multiply_five = list(range(5,101,5))
print('multiply_five list = ',multiply_five)
multiply_five.reverse()
print('multiply_five list reversed = ',multiply_five)
In [20]:
# [ ] Create two lists: fours & more_fours containing multiples of four from 4 to 44
# [ ] combine and print so that the output is mirrored [44, 40,...8, 4, 4, 8, ...40, 44]
#Answer:
fours = list(range(4,45,4))
more_fours = list(range(4,45,4))
more_fours.reverse()
print("fours mirrored = ",more_fours+fours)
In [22]:
# [ ] review and run example
quiz_scores = [20, 19, 20, 15, 20, 20, 20, 18, 18, 18, 19]
# use .sort()
quiz_scores.sort()
print("quiz_scores:", quiz_scores)
In [23]:
# [ ] review and run example
game_points = [3, 14, 0, 8, 21, 1, 3, 8]
# use sorted()
sorted_points = sorted(game_points)
print("game_points:", game_points)
print("sorted_points:", sorted_points)
In [24]:
# [ ] review and run example
cities_1 = ["Dubai", "Mexico City", "São Paulo", "Hyderabad"]
print("Unsorted", cities_1)
cities_1.sort()
print("Sorted", cities_1)
In [25]:
# [ ] print cites from visited_cities list in alphbetical order using .sort()
# [ ] only print cities that names start "Q" or earlier
visited_cities = ["New York", "Shanghai", "Munich", "Toyko", "Dubai", "Mexico City", "São Paulo", "Hyderabad"]
#Answer:
visited_cities.sort()
print(visited_cities)
In [26]:
# [ ] make a sorted copy (sorted_cities) of visited_cities list
# [ ] remove city names 5 characters or less from sorted_cities
# [ ] print visitied cites and sorted cities
visited_cities = ["New York", "Shanghai", "Munich", "Tokyo", "Dubai", "Mexico City", "São Paulo", "Hyderabad"]
#Answer:
sorted_cities = sorted(visited_cities)
for city in sorted_cities:
if len(city) <= 5:
sorted_cities.remove(city)
print('visited_cities ',visited_cities)
print('sorted_cities ',sorted_cities)
step 1 get user input to build add_animals list
In [27]:
# [ ] build a list (add_animals) using a while loop, stop adding when an empty string is entered
#add_animals = []
#Answer:
add_animals = []
while True:
animal = input('Type animal name: ')
if (len(animal)==0):
break
add_animals.append(animal)
step 2 Merge the lists: add_animals into animals
In [29]:
# [ ] extend the lists into animals, then sort
animals = ["Chimpanzee", "Panther", "Wolf", "Armadillo"]
#Answer:
animals.extend(add_animals)
animals.sort()
print("animals = ",animals)
step 3 Allow animals list to be viewed alpha or reverse alpha order
In [33]:
# [ ] get input if list should be viewed alpha or reverse alpha and display list
#Answer:
viewed = "a"
viewed = input("Type how you want to view the animal, alpha(a) or reverse(r)")
if (viewed.lower()=='a'):
print("sorted alpha",sorted(animals))
else:
sorted(animals).reverse()
print("reversed alpha",animals)
In [ ]:
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