实操一下<python cookbook>第三版1

这几天没写代码，

练一下代码。

找的书是<python cookbook>第三版的电子书。

*这个操作符，运用得好，确实少很多代码，且清晰易懂。

p = (4, 5)
x, y = p
print(x)
print(y)

s = 'Hello'
a, b, c, d, e = s
print(a, b, c)

data = ['ACME', 50, 91.1, (2012, 12, 21)]
_, shares, price, _ = data
print(shares, price)

def drop_first_last(grades):
    first, *middle, last = grades
    return middle

print(drop_first_last([23, 34, 45, 56, 67, 78, 12, 23]))

record = ('Dave', 'dave@example.com', '773-555-1212', '847-555-1212')
name, email, *phone_numbers = record
print(name, email, phone_numbers)

*trailing_qtrs, current = [10, 8, 7, 1, 9, 5, 10, 3]
trailing_avg = sum(trailing_qtrs) / len(trailing_qtrs)

print(current, trailing_avg)

records = [
    ('foo', 1, 2),
    ('bar', 'hello'),
    ('foo', 3, 4),
]

def do_foo(x, y):
    print('foo', x, y)

def do_bar(s):
    print('bar', s)

for tag, *args in records:
    if tag == 'foo':
        do_foo(*args)
    elif tag == 'bar':
        do_bar(*args)

line = 'nobody:*:-2:-2:Unprivileged User:/var/empty:/usr/bin/false'
uname, *fields, homedir, sh = line.split(':')
print(uname, homedir, sh)

record = ('ACME', 50, 123.45, (12, 18, 2012))
name, *_, (*_, year) = record
print(name, year)

items = [1, 10, 7, 4, 5, 9]
head, *tail = items
print(head, tail)

def sum(items):
    head, *tail = items
    return head + sum(tail) if tail else head
print(sum(items))

输出：

4
5
H e l
50 91.1
[34, 45, 56, 67, 78, 12]
Dave dave@example.com ['773-555-1212', '847-555-1212']
3 7.142857142857143
foo 1 2
bar hello
foo 3 4
nobody /var/empty /usr/bin/false
ACME 2012
1 [10, 7, 4, 5, 9]
36

Process finished with exit code 0