class A():
pass
if xxxx("A"):
print("A exists")
else:
print("A not exists")
class A():
pass
if xxxx("A"):
print("A exists")
else:
print("A not exists")you can use the method of comparing hacky:
def is_class_exists(class_name):
if not class_name.isidentifier():
return False
try:
return isinstance(eval(class_name), type)
except NameError:
return False< H2 > 1. Question: < H2 > like the title, how does the chart displayed by matplotlib.pyplot.show () in pycharm pop up to sciview,? < H2 > 2. Code: < H2 > import matplotlib.pyplot as plt import matplotlib.animation as animation from matplotlib impo...
The question is written on the title, is there any way to be spaced by BAN, when it is applied too fast in crawlers? Or is it that there is no interval in this kind of concurrency? ...
the newly installed win7 system, Ann python is, the installation package setup comes out of this, which I have encountered before. I forgot how to solve it. ...
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the settings of the webmaster document are as follows from pytz import utc from apscheduler.schedulers.background import BackgroundScheduler from apscheduler.jobstores.mongodb import MongoDBJobStore from apscheduler.jobstores.sqlalchemy import SQLAlche...
the problem is like a question. I ll describe the details in detail. asked the same question on Zhihu when I was self-taught python crawler, I came into contact with MongoDB, to install according to the URL given by rookie tutorial . Visual obser...
1. (requirements) can be deleted by searching for matching messages based on time or sender. 2. (background) I have used the two libraries imaplib and imapclient, one official and one third party, and Poplib does not have the search function. Although...
as shown in the figure below, does SQLAlchemy have a simple way to directly declare that the specified field is not mapped serialized? for example, does java s Hibernate framework have such a function? (although there are other "indirect " solut...
python3.6 pip 9.0.3 install shapely 1.6.4 error as shown in figure ...
the official WeChat of the school has an one-click function to check grades, and I have always wanted to be able to do it. Now I am learning python, and I am going to use it to practice, but I made a 500th error during the interview. here is the code:...
there are two built-in functions that have very similar functional descriptions: >>> help(exec) Help on built-in function exec in module builtins: exec(source, globals=None, locals=None, ) Execute the given source in the context of globa...
python setup.py register enter the account password and then 410: Server response (410): Project pre-registration is no longer required or support ed, so continue directly to uploading files. ...
the code is as follows: recode1 = table_out.find ({}). Sort ([( "_ id ", 1)]) .limit (10000) print ( total: , recode1.count ()) directly understand that the number of count () given by print should be 10,000, but what is currently output is the tota...
use the requests proxy module and do not change the ip address after success < hr > Code: import requests from bs4 import BeautifulSoup url=r http: ip.chinaz.com proxy={ http : http: 177.130.55.164:20183 , https : https: 177.1...
python converts "3 hours and 10 minutes " to "190 minutes " solution ...
We know that the collections of the python built-in module has a lot of useful operations. for example: from collections import Counter -sharp -sharp top n user_counter = Counter("abbafafpskaag") print(user_counter.most_common(3)) -sharp[( ...
check to see that celery and airflow, do not support Windows in the actual experiment. is there another way to implement this? can only reinstall a linux. ...
1. Recently, I have studied python, again to see the slicing part of Liao Xuefeng s tutorial. I would like to ask how this code realizes that the spaces on both sides are not displayed in the output by slicing . def trim(s): if s[:1] != and ...
question: recently I was learning the perceptron model and wanted to draw the following picture, but found that the + - sign in the following picture could not be drawn. drawing code from elsewhere, where Perceptron is a class implemented i...
the data obtained from the database is such a dictionary { q_1 : 9, q_2 : 12, q3 : 22, q4 : 2, q5 : 6, w_1 : 9, w_2 : 12, w_3 : 22, w_4 : 2, w_5 : 6, e_1 : 9, e_2 : 12, e_3 : 22, e_4 : 2, e_5 : 6...