What is the difference between ‘+=’ and ‘=+’? [duplicate]
i+=1 is the same as i=i+1, whereas i=+1 just means i=(+1).
python
Nesting ‘WITH’ statements in Python
I found the solution in python’s doc. You may want to have a look at this (Python 3) or this (Python 2) If you are running python 2.7+ you can use it like this: with open(file1) as fsock1, open(file2, ‘a’) as fsock2: fstring1 = fsock1.read() fstring2 = fsock2.read() This way you avoid unnecessary indentation.
Django: How to override unique_together error message?
You can do this since Django 1.7 from django.forms import ModelForm from django.core.exceptions import NON_FIELD_ERRORS class ArticleForm(ModelForm): class Meta: error_messages = { NON_FIELD_ERRORS: { ‘unique_together’: “%(model_name)s’s %(field_labels)s are not unique.”, } }
Using Python decorators to retry request
You can use a decorator like this and handle your own exception. def retry(times, exceptions): “”” Retry Decorator Retries the wrapped function/method `times` times if the exceptions listed in “exceptions“ are thrown :param times: The number of times to repeat the wrapped function/method :type times: Int :param Exceptions: Lists of exceptions that trigger a retry … Read more
How do I persist to disk a temporary file using Python?
hop is right, and dF. is incorrect on why the error occurs. Since you haven’t called f.close() yet, the file is not removed. The doc for NamedTemporaryFile says: Whether the name can be used to open the file a second time, while the named temporary file is still open, varies across platforms (it can be … Read more
Remove whitespaces in XML string
The easiest solution is probably using lxml, where you can set a parser option to ignore white space between elements: >>> from lxml import etree >>> parser = etree.XMLParser(remove_blank_text=True) >>> xml_str=””‘<root> >>> <head></head> >>> <content></content> >>> </root>”’ >>> elem = etree.XML(xml_str, parser=parser) >>> print etree.tostring(elem) <root><head/><content/></root> This will probably be enough for your needs, but … Read more
How to check if an element is an empty list in pandas?
You can do this: df[df[“col”].str.len() != 0] Example: import pandas as pd df = pd.DataFrame({“col”: [[1], [2, 3], [], [4, 5, 6], []]}, dtype=object) print(df[df[“col”].str.len() != 0]) # col # 0 [1] # 1 [2, 3] # 3 [4, 5, 6]
Python in docker – RuntimeError: can’t start new thread
Solution to this problem was to upgrade docker from version 18.06.1-ce to 20.10.7. Why? This is because the default seccomp profile of Docker 20.10.9 is not adjusted to support the clone() syscall wrapper of glibc 2.34 adopted in Ubuntu 21.10 and Fedora 35. Source: ubuntu:21.10 and fedora:35 do not work on the latest Docker (20.10.9)
Django: Increment blog entry view count by one. Is this efficient?
You can use F() objects for this. Here is how you import F: from django.db.models import F New in Django 1.1. Calls to update can also use F() objects to update one field based on the value of another field in the model. This is especially useful for incrementing counters based upon their current value. … Read more
How to force scrapy to crawl duplicate url?
You’re probably looking for the dont_filter=True argument on Request(). See http://doc.scrapy.org/en/latest/topics/request-response.html#request-objects