listの扱い: 悪いコードと良いコード

悪いコード

# Filter elements greater than 4
a = [3, 4, 5]
b = []
for i in a:
    if i > 4:
        b.append(i)
# Add three to all list members.
a = [3, 4, 5]
for i in range(len(a)):
    a[i] += 3

良いコード

a = [3, 4, 5]
b = [i for i in a if i > 4]
# Or:
b = filter(lambda x: x > 4, a)

a = [3, 4, 5]
a = [i + 3 for i in a]
# Or:
a = map(lambda i: i + 3, a)

a = [3, 4, 5]
for i, item in enumerate(a):
    print i, item
# prints
# 0 3
# 1 4
# 2 5