← Назад
num = [1, 4, -5, 10, -7, 2, 3, -1]
filtered_and_squared = []
for number in num:
if number > 0:
filtered_and_squared.append(number ** 2)
print filtered_and_squared
# [1, 16, 100, 4, 9]
или
num = [1, 4, -5, 10, -7, 2, 3, -1]
filtered_and_squared = map(lambda x: x ** 2, filter(lambda x: x > 0, num))
print filtered_and_squared
# [1, 16, 100, 4, 9]
или
num = [1, 4, -5, 10, -7, 2, 3, -1]
filtered_and_squared = [x**2 for x in num if x > 0]
print filtered_and_squared
# [1, 16, 100, 4, 9]
num = [1, 4, -5, 10, -7, 2, 3, -1]
filtered_and_squared = (x**2 for x in num if x > 0)
print filtered_and_squared
# <generator object <genexpr> at 0x00583E18>
for item in filtered_and_squared:
print item
# 1, 16, 100, 4,9
num = [1, 4, -5, 10, -7, 2, 3, -1]
def square_generator(optional_parameter):
return (x ** 2 for x in num if x > optional_parameter)
print square_generator(0)
# <generator object <genexpr> at 0x004E6418>
# Option I
for k in square_generator(0):
print k
# 1, 16, 100, 4, 9
# Option II
g = list(square_generator(0))
print g
# [1, 16, 100, 4, 9]
Так же, вы можете использовать функцию zip для работы с двумя и более элементами за раз:
alist = ['a1', 'a2', 'a3']
blist = ['1', '2', '3']
for a, b in zip(alist, blist):
print a, b
# a1 1
# a2 2
# a3 3
Пример двухуровневого генератора с использованием os.walk():
import os
def tree(top):
for path, names, fnames in os.walk(top):
for fname in fnames:
yield os.path.join(path, fname)
for name in tree('C:\Users\XXX\Downloads\Test'):
print name
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