我试图使用Pandas在每列中找到不同值的计数.这就是我做的.
import pandas as pd
import numpy as np
# Generate data.
NROW = 10000
NCOL = 100
df = pd.DataFrame(np.random.randint(1, 100000, (NROW, NCOL)),
columns=['col' + x for x in np.arange(NCOL).astype(str)])
我需要计算每列的不同元素的数量,如下所示:
col0 9538
col1 9505
col2 9524
最有效的方法是什么,因为此方法将应用于大小超过1.5GB的文件？
根据答案,df.apply(lambda x: len(x.unique()))是最快的(笔记本).
%timeit df.apply(lambda x: len(x.unique()))
10 loops, best of 3: 49.5 ms per loop
%timeit df.nunique()
10 loops, best of 3: 59.7 ms per loop
%timeit df.apply(pd.Series.nunique)
10 loops, best of 3: 60.3 ms per …
我正在尝试实施工厂设计模式,并且到目前为止已经做到了这一点.
import abc
class Button(object):
__metaclass__ = abc.ABCMeta
html = ""
def get_html(self, html):
return self.html
class ButtonFactory():
def create_button(self, type):
baseclass = Button()
targetclass = type.baseclass.capitalize()
return targetclass
button_obj = ButtonFactory()
button = ['image', 'input', 'flash']
for b in button:
print button_obj.create_button(b).get_html()
输出应该是所有按钮类型的HTML.
我得到这样的错误
AttributeError: 'str' object has no attribute 'baseclass'
我正在尝试实现一个具有不同变体的类,例如ImageButton,InputButton和FlashButton.根据地点的不同,可能需要为按钮创建不同的html
我试图提交以及从DB同时查询结果,我最终得到了这个错误.
sqlalchemy.exc.InvalidRequestError: This session is in 'committed' state; no further SQL can be emitted within this transaction.
完全追溯:
Traceback (most recent call last):
File "C:\Python34\lib\site-packages\flask\app.py", line 1836, in __call__
return self.wsgi_app(environ, start_response)
File "C:\Python34\lib\site-packages\flask\app.py", line 1820, in wsgi_app
response = self.make_response(self.handle_exception(e))
File "C:\Python34\lib\site-packages\flask\app.py", line 1403, in handle_exception
reraise(exc_type, exc_value, tb)
File "C:\Python34\lib\site-packages\flask\_compat.py", line 33, in reraise
raise value
File "C:\Python34\lib\site-packages\flask\app.py", line 1817, in wsgi_app
response = self.full_dispatch_request()
File "C:\Python34\lib\site-packages\flask\app.py", line 1477, in full_dispatch_request
rv = self.handle_user_exception(e)
File "C:\Python34\lib\site-packages\flask\app.py", line 1381, …我试图创建一个随机的真实,整数,字母数字,字母字符串,然后写入文件,直到文件大小达到10MB.
代码如下.
import string
import random
import time
import sys
class Generator():
def __init__(self):
self.generate_alphabetical_strings()
self.generate_integers()
self.generate_alphanumeric()
self.generate_real_numbers()
def generate_alphabetical_strings(self):
return ''.join(random.choice(string.ascii_lowercase) for i in range(12))
def generate_integers(self):
return ''.join(random.choice(string.digits) for i in range(12))
def generate_alphanumeric(self):
return ''.join(random.choice(self.generate_alphabetical_strings() +
self.generate_integers()) for i in range(12))
def _insert_dot(self, string, index):
return string[:index].__add__('.').__add__(string[index:])
def generate_real_numbers(self):
rand_int_string = ''.join(random.choice(self.generate_integers()) for i in range(12))
return self._insert_dot(rand_int_string, random.randint(0, 11))
from time import process_time
import os
a = Generator()
t = process_time()
inp = open("test.txt", …我是Python的新手,我无法理解Python中的服务器概念.
首先是什么是WSGI,什么是Wsgiref和Werkzeug,它们与CherryPy WSGI服务器,Gunicorn,Tornado(HTTP服务器通过wsgi.WSGIContainer),Twisted Web,uWSGI,Waitress WSGI Server有何不同.
如果我需要从头开始开发Web应用程序,我的意思是从头开始,我应该从哪里开始,我的公司需要一个自定义框架,而应用程序是基于关键的性能开销.
请帮助解释它们的不同之处.
PS我不是编程的初学者.
我正在尝试实现我自己的wsgiref版本用于学习目的,我最终在这里:
from wsgiref.simple_server import make_server
class DemoApp():
def __init__(self, environ, start_response):
self.environ = environ
self.start = start_response
def __iter__(self, status):
self.status = '200 OK'
response_headers = [('Content-type','text/plain')]
self.start(status, response_headers)
return ["Hello World"]
if __name__ == '__main__':
httpd = make_server('', 1000, DemoApp)
print("Serving on port 1000")
httpd.serve_forever()
当我转到端口1000时,我收到属性错误.
AttributeError: 'NoneType' object has no attribute 'split'
我在哪里留下错误？
堆栈跟踪:
Serving on port 1000
Traceback (most recent call last):
File "C:\Python27\lib\wsgiref\handlers.py", line 86, in run
self.finish_response()
File "C:\Python27\lib\wsgiref\handlers.py", line 131, in finish_response
self.close()
File …ADT is the set of operations. ADT's are mathematical abstractions.
这是否意味着ADT与班级相同或者我是否混淆在一起？
我是Django的新手,并试图弄清楚url如何在Django中工作.
我的应用程序是urls.py
from django.conf.urls import url, patterns
import views
urlpatterns = patterns('',
url(r'^$', views.index, name='index'))
项目urls.py
from django.conf.urls import patterns, include, url
from django.contrib import admin
admin.autodiscover()
urlpatterns = patterns('',
url(r'^admin/', include(admin.site.urls)),
url(r'^app/', include('app.urls')),
)
APPEND_SLASH = True坐落在settings.py和应用程序包含在INSTALLED_APPS.
当我去的时候,我得到了Page Not Foundlocalhost:8000/app.
现在我也无法前往localhost:8000/admin.
RuntimeError at /admin/
maximum recursion depth exceeded
app的views.py
from django.http import HttpResponse
def index(request):
return HttpResponse("This is Hello")
Settings.py
import os
BASE_DIR = …我在这里是NOOBish,但由于The Heartbleed Bug,我对托管代码非常感兴趣.
我最近在HN读到这句话,其中说:
C和其他没有内存检查的语言不适合编写安全代码.显然不合适.它们需要被限制为编写一个小型核心系统,最好小到可以使用正式(基于证据的)方法进行检查,其余所有应用程序逻辑都应该使用托管代码(例如C#, Java,或其他 - 我没有偏好).
那么Python是一种托管代码语言还是托管代码只是一个Microsoft术语？
这行在python 2.7.6中完美运行,但在Python 3.3.5中失败.我如何hex在Python 3中解码为值.
return x.replace(' ', '').replace('\n', '').decode('hex')
追溯
AttributeError: 'str' object has no attribute 'decode'