Examples of folds in Python

fold.py

#
# fold

def sum_nums(lst):
    sum = 0
    for el in lst:
        sum = sum + el
    return sum

def sum_strs(lst):
    sum = ""
    for el in lst:
        sum = sum + el
    return sum

print(sum_nums([1, 2, 3]))
print(sum_strs(["A", "B", "C"]))

init = 0

def f(a, b):
    return a + b

def fold(lst):
    acc = init
    for el in lst:
        acc = f(acc, el)
    return acc


print(fold([1, 2, 3]))

def ave_grade(lst):
    acc = 0
    for el in lst:
        acc = f(acc, el)
    return acc / len(lst)


print(ave_grade([80, 92, 65, 72])) # 77.25

# [fold] Create a function that finds the minimum of a list of numbers

def min_of_2(a, b):
    if (a < b):
        return a
    else:
        return b

def min_num(lst):
    acc = lst[0]
    for el in lst:
        acc = min_of_2(acc, el)
    return acc

print(min_num([80, 92, 65, 72])) # 65
print(min_num(["A", "B", "C"])) # "A"


# fold] Create a function that counts the number of vowels in a string

def to_lower(ch):
    return ch.lower()

def is_vowel(upper_ch):
    ch = to_lower(upper_ch)
    return ch == "a" or ch == "e" or ch == "i" or ch == "o" or ch == "u"


def count_vowel(count, ch):
    if (is_vowel(ch)):
        return count + 1
    else:
        return count

def num_vowels(lst):
    count = 0
    for el in lst:
        count = count_vowel(count, el)
    return count

print(num_vowels("Jheno Astillero Mollejon")) # 9

# create a function that counts the number of gmail.com email addresses in a list
def count_gmail(count, email):
    if (email[-10:] == "@gmail.com"):
        return count + 1
    else:
        return count

def num_gmail(lst):
    count = 0
    for email in lst:
        count = count_gmail(count, email)
    return count

print(num_gmail([ "[email protected]", "[email protected]", "[email protected]" ]))

# Determine whether every name in the list begins with J

def begins_with_j(acc, el):
    return acc and (el[0] == 'j' or el[0] == 'J')

    # if (acc == False):
    #     return False
    # elif (el[0] == 'j' or el[0] == 'J'):
    #     return True
    # else:
    #     return False

def all_begins_with_j(lst):
    acc = True
    for el in lst:
        acc = begins_with_j(acc, el)
    return acc

print(all_begins_with_j(["jheno", "joshua", "janice"]))
print(all_begins_with_j(["jheno", "nisha", "janice"]))