小编ama*_*man的帖子

使用map和有map_async什么区别？将项目从列表分发到4个进程后,它们是否没有运行相同的功能？

那么假设两者都在运行异步和并行是错误的吗？

def f(x):
   return 2*x

p=Pool(4)
l=[1,2,3,4]
out1=p.map(f,l)
#vs
out2=p.map_async(f,l)

cython在ipython笔记本中使用时,我看到下面的错误.怎么了？

%load_ext cythonmagic
/usr/local/lib/python2.7/dist-packages/IPython/extensions/cythonmagic.py:21: UserWarning: The Cython magic has been moved to the Cython package
      warnings.warn("""The Cython magic has been moved to the Cython package""")



%%cython
def fib(int n):
    cdef int a,b,i
    for i in range(n):
        a,b=a+b,b
    return a 

ERROR: Cell magic `%%cython` not found.

我正在尝试validate()调用覆盖函数serializers.is_valid()，但它没有被调用。

序列化程序.py

class LoginSerializer(serializers.Serializer):
    email = serializers.EmailField(max_length=255,required=True)
    password = serializers.CharField(max_length=128,required=True)


    def validate(self,data):
       '''
       Check for invalid email.
       & blank email and password. 
       '''

       print 'hey i am in login'

       if data['email'] is '':
           raise serializers.ValidationError("Email cannot be empty.")
       if data['password'] is '':
          raise serializers.ValidationError("Password cannot be empty.")
       try:
          validate_email(data['email'])
       except ValidationError:
          raise serializers.ValidationError("The email is not a valid email address.")
       return data

视图.py

class LoginAPI(APIView):
    permission_classes = (permissions.AllowAny,)
    serializer = LoginSerializer

    def post(self, request):
       data = …

我使用 scrapy 和 selenium webdrivers 进行网络抓取。但我发现 selenium webdriver 非常慢，但我发现提取 webelement 的 CSS 属性更容易，例如。

webElement.value_of_css_property('font-size')

如何仅使用 scrapy 而不使用 selenium webdriver 来实现这一点？

当我从nltk执行stanford解析器时,我得到以下结果.

(S (VP (VB get) (NP (PRP me)) (ADVP (RB now))))

但我需要它的形式

S -> VP
VP -> VB NP ADVP
VB -> get
PRP -> me
RB -> now

如何使用递归函数获得此结果.有内置功能吗？

当我在终端执行ipython时,我看到以下错误

aman@ebex-MacBookPro:~/ipython_work$ ipython                                                                                       
Traceback (most recent call last):                                                                                                 
  File "/usr/local/bin/ipython", line 5, in <module>                                                                               
    from pkg_resources import load_entry_point                                                                                     
  File "/usr/local/lib/python2.7/dist-packages/pkg_resources/__init__.py", line 3141, in <module>                                  
    @_call_aside                                                                                                                   
  File "/usr/local/lib/python2.7/dist-packages/pkg_resources/__init__.py", line 3127, in _call_aside                               
    f(*args, **kwargs)                                                                                                             
  File "/usr/local/lib/python2.7/dist-packages/pkg_resources/__init__.py", line 3154, in _initialize_master_working_set            
    working_set = WorkingSet._build_master()                                                                                       
  File "/usr/local/lib/python2.7/dist-packages/pkg_resources/__init__.py", line 640, in _build_master                              
    ws.require(__requires__)                                                                                                       
  File "/usr/local/lib/python2.7/dist-packages/pkg_resources/__init__.py", line 941, in require                                    
    needed = self.resolve(parse_requirements(requirements))                                                                        
  File "/usr/local/lib/python2.7/dist-packages/pkg_resources/__init__.py", line 828, in resolve                                    
    raise DistributionNotFound(req, requirers)                                                                                     
pkg_resources.DistributionNotFound: The 'pathlib2' distribution was not found and is required by ipython   

就在我跟随之前 …

我想在使用scrapy和selenium进行刮擦时禁用JavaScript.这样做的动机是提高刮削速度.我发现了对Firefox驱动程序的偏好,但没有找到PhantomJS.

firefox_profile = webdriver.FirefoxProfile()
firefox_profile.set_preference("javascript.enabled", False)

driver = webdriver.Firefox(firefox_profile=firefox_profile)
driver.get('http://www.quora.com/')

如何为PhantomJS webdriver做到这一点？

我是NLP概念的新手,我对词汇化解析器和依赖解析器的概念有点困惑.它们是相同的,还是不同的是它们的不同之处.请帮助理解.我正在使用斯坦福解析器java包.谢谢

我有输入:

callme
senditnow
runningcar

我怎么能提取像叫我,现在发送,跑车这样的词.在python中有任何库使用一些字典来做那件事.

我无法从sklearn导入hmm模块。

from sklearn import hmm

我收到错误消息：

ImportError: cannot import name hmm

我想根据从斯坦福解析器检索的语法生成句子，但 NLTK 无法解释 PRP$。

from nltk.parse.stanford import StanfordParser
from nltk.grammar import CFG
from nltk.parse.generate import generate

sp=StanfordParser(model_path='/home/aman/stanford_resource/stanford-parser-full-2014-06-16/stanford-parser-3.4-models/edu/stanford/nlp/models/lexparser/englishPCFG.ser.gz',path_to_jar='/home/aman/stanford_resource/stanford-parser-full-2014-06-16/stanford-parser.jar',path_to_models_jar='/home/aman/stanford_resource/stanford-postagger-full-2014-08-27/stanford-postagger-3.4.1.jar')
sent1='He killed the tiger in his pants'
parse_result=sp.raw_parse(sent1)
grammar_list=[]

for p in parse_result:
    l=p.productions()
    grammar_string='\n'.join(map(str,l))
    grammar=CFG.fromstring(grammar_string)
    #grammar_list.append(grammar)
    #for s in generate(grammar,n=3):
    #    print s




ValueError: Unable to parse line 11: NP -> PRP$ NNS
Expected a nonterminal, found: $ NNS

它怎么能工作。我是否应该专门针对这些语法类别指导 nltk。