# Sequences as conventional interfaces
def fib(n):
    if n == 0:
        return 0
    elif n == 1:
        return 1
    return fib(n - 1) + fib(n - 2)

is_even = lambda x: x % 2 == 0

fibs = tuple(map(fib, range(8)))
even_fibs = tuple(filter(is_even, fibs))
sum(even_fibs)

# Generator expressions
even_fibs2 = tuple(fib(n) for n in range(8) if is_even(fib(n)))

# Reducing a sequence
from operator import mul
from functools import reduce
reduce(mul, (1, 2, 3, 4, 5), 1)

def accumulate(combiner, start, n, term):
    """Accumulate a sequence of n terms with the given combiner and
    initial value.

    >>> accumulate(mul, 1, 4, lambda x: x * x)
    576
    """
    return reduce(combiner, map(term, range(1, n + 1)), start)

# More functions on iterables (bonus)
a, b = (1, 2, 3), (4, 5, 6, 7)
for x, y in zip(a, b):
    print(x + y)

from itertools import product, combinations
tuple(product(a, b[:2]))
tuple(combinations(a, 2))

# Lists
a = [3, 1, 2]
b = sorted(a)
c, d = a, a[:]
c[0] = 4
d[0] = 5
a[1:2] = [7, 8, 9]

# Objects
type(4)
type([4])

(4).real, (4).imag
[1, 2, 1, 4].count(1)

[1, 2, 1, 4] is [1, 2, 1, 4]
[1, 2, 1, 4] == [1, 2, 1, 4]

e, f = 1e12, 1e12
e is f
True
e = 1e12
f = 1e12
e is f

# List comprehensions
g = [3 / x for x in range(4) if x != 0]

# Dictionaries
eras = {'cain': 2.79,
        'bumgarner': 3.37,
        'vogelsong': 3.37,
        'lincecum': 5.18,
        'zito': 4.15}

total_era = 0
for pitcher in eras:
    total_era += eras[pitcher]
total_era / len(eras)

eras['lincecum'] = 3.0

new_eras = {p: round(eras[p]-1, 3) for p in eras}