Repeating Code Using Loops

1.

for phenotype in celegans_phenotypes:
    print(phenotype)

2.

for value in half_lives:
    print(value, end=' ')

3.

more_whales = []
for count in whales:
    more_whales.append(count + 1)

4. a.

alkaline_earth_metals = [[4, 9.012], [12, 24.305],
                         [20, 40.078], [38, 87.62],
                         [56, 137.327], [88, 226]]
b.
for inner_list in alkaline_earth_metals:
    print(inner_list[0])
    print(inner_list[1])
c.
number_and_weight = []
for inner_list in alkaline_earth_metals:
    number_and_weight.append(inner_list[0])
    number_and_weight.append(inner_list[1])

5.

def mystery_function(values):
    """ (list) -> list

    Return a copy of the list, values, and the sublists it contains.
    The top-level sublists have their elements reversed in the returned
    list.

    >>> mystery_function([[1, 2, 3], [4, 5, 6]])
    [[3, 2, 1], [6, 5, 4]]
    """ 

    result = []
    for sublist in values:
        # Copy the sublist in reverse order by inserting each
        # element to the front of the new sublist.
        result.append([sublist[0]])
        for i in sublist[1:]:
            result[-1].insert(0, i)

    return result

6.

text = "" 
while text.lower() != "quit":
    text = input("Please enter a chemical formula (or 'quit' to exit): ")
    if text == "quit":
        print("…exiting program")
    elif text == "H2O":
        print("Water")
    elif text == "NH3":
        print("Ammonia")
    elif text == "CH4":
        print("Methane")
    else:
        print("Unknown compound")

7.

total = 0
for population in country_populations:
    total += population

8. a.

if rat_1[0] > rat_2[0]:
    print("Rat 1 weighed more than rat 2 on day 1.")
else:
    print("Rat 1 weighed less than rat 2 on day 1.")

b.

if rat_1[0] > rat_2[0] and rat_1[-1] > rat_2[-1]:
    print("Rat 1 remained heavier than Rat 2.")
else
    print("Rat 2 became heavier than Rat 1.")

c.

if rat_1[0] > rat_2[0]:
    if rat_1[-1] > rat_2[-1]:
        print("Rat 1 remained heavier than Rat 2.")
    else:
        print("Rat 2 became heavier than Rat 1.")
else
    print("Rat 2 became heavier than Rat 1.")

9.

for number in range(33, 50):
    print(number)

10.

for number in range(10):
    print(10 - number, end=' ')

11.

sum = 0
count = 0
for number in range(2,23):
    sum += number
    count += 1

average = sum / count

12.

def remove_neg(num_list):
    index = 0
    while index < len(num_list):
        if num_list[index] < 0:
            del num_list[index]
        else:
            index += 1

13.

for width in range(1, 8):
    print('T' * width)

14.

for width in range(1, 8):
    print(' ' * (7 - width), 'T' * width, sep='')

15.

width = 1
while width < 8:
    print('T' * width)
    width += 1

width = 1
while width < 8:
    print(' ' * (7 - width), 'T' * width, sep='')
    width += 1

16. a.

week = 1
while rat_1_weight[week] / rat_1_weight[0] - 1 < .25:
    week += 1

print(week) 

b.

week = 0
while rat_1_weight[week] / rat_2_weight[week] - 1 < .10:
    week += 1

print(week)