我想更改下面的代码
for directory, dirs, files in os.walk(directory_1):
do_something()
for directory, dirs, files in os.walk(directory_2):
do_something()
到此代码:
for directory, dirs, files in os.walk(directory_1) + os.walk(directory_2):
do_something()
我得到了错误:
不支持+:'generator'和'generator'的操作数类型
如何在Python中连接两个生成器?
当前回答
Itertools.chain()应该做到这一点。它接受多个可迭代对象，并逐个产生结果，大致相当于:
def chain(*iterables):
for it in iterables:
for element in it:
yield element
使用的例子:
from itertools import chain
g = (c for c in 'ABC') # Dummy generator, just for example
c = chain(g, 'DEF') # Chain the generator and a string
for item in c:
print(item)
输出:
A
B
C
D
E
F
其他回答
Itertools.chain()应该做到这一点。它接受多个可迭代对象，并逐个产生结果，大致相当于:
def chain(*iterables):
for it in iterables:
for element in it:
yield element
使用的例子:
from itertools import chain
g = (c for c in 'ABC') # Dummy generator, just for example
c = chain(g, 'DEF') # Chain the generator and a string
for item in c:
print(item)
输出:
A
B
C
D
E
F
代码示例:
from itertools import chain
def generator1():
for item in 'abcdef':
yield item
def generator2():
for item in '123456':
yield item
generator3 = chain(generator1(), generator2())
for item in generator3:
print item
如果你想从一个已知目录之前和之后获取文件路径列表，你可以这样做:
for r,d,f in os.walk(current_dir):
for dir in d:
if dir =='after':
after_dir = os.path.abspath(os.path.join(current_dir, dir))
for r,d,f in os.walk(after_dir):
after_flist.append([os.path.join(r,file)for file in f if file.endswith('json')])
elif dir =='before':
before_dir = os.path.abspath(os.path.join(current_dir, dir))
for r,d,f in os.walk(before_dir):
before_flist.append([os.path.join(r,file)for file in f if file.endswith('json')])
我知道有更好的答案，这是我觉得简单的代码。
使用itertools.chain.from_iterable，你可以这样做:
def genny(start):
for x in range(start, start+3):
yield x
y = [1, 2]
ab = [o for o in itertools.chain.from_iterable(genny(x) for x in y)]
print(ab)
简单的例子:
from itertools import chain
x = iter([1,2,3]) #Create Generator Object (listiterator)
y = iter([3,4,5]) #another one
result = chain(x, y) #Chained x and y
