What is the equivalent of this SQL statement in django? How do I implement this in django? I tried But that did not work. How do i implement this? Answer Use __contains or __icontains (case-insensitive): The SQL equivalent is @Dmitri’s answer below covers patterns like ‘pattern%’ or ‘%…
Tag: python
Python string ‘in’ operator implementation algorithm and time complexity
I am thinking of how the in operator implement, for instance In CPython, which algorithm is used to implement the string match, and what is the time complexity? Is there any official document or wiki about this? Answer It’s a combination of Boyer-Moore and Horspool. You can view the C code here: Fast se…
How to find parent elements by python webdriver?
Is there any methods for python+selenium to find parent elements, brother elements, or child elements just like driver.find_element_parent? or driver.find_element_next? or driver.find_element_previous? eg: I’ve tried like below, but fail: How can I get the parent of input element and then, finally, get …
Finding the intersection between two series in Pandas
I have two series s1 and s2 in pandas and want to compute the intersection i.e. where all of the values of the series are common. How would I use the concat function to do this? I have been trying to work it out but have been unable to (I don’t want to compute the intersection on the indices of
Django Queryset Filter Missing Quotes
I have a list and I want to filter my Queryset when any of these items is found in a foreign table’s non-primary key ‘test’. So I write something like this: This returns an empty list. When I look at the SQL query it generated, I get: Whereas what it should have been is this: Without the quo…
How can I use list comprehensions to process a nested list?
I have this nested list: I want to convert each element in l to float. I have this code: How can I solve the problem with a nested list comprehension instead? See also: How can I get a flat result from a list comprehension instead of a nested list? Answer Here is how you would do this with a nested
How to create recalculating variables in Python
Suppose I have the code: The question is: how to keep b updated on each change in a? E.g., after the above code I would like to get: print(b) to be 5, not 4. Of course, b can be a function of a via def, but, say, in IPython it’s more comfortable to have simple variables. Are there way to
Python argparse conditional requirements
How do I set up argparse as follows: For example, There are a number of similar questions here, but either they don’t address this situation or I don’t understand. Python 2.7 if that matters. Answer A subparser (as suggested in comments) might work. Another alternative (since mutually_exclusive_gr…
Local variable referenced before assignment? [duplicate]
This question already has answers here: UnboundLocalError trying to use a variable (supposed to be global) that is (re)assigned (even after first use) (14 answers) Closed 6 months ago. I am using the PyQt library to take a screenshot of a webpage, then reading through a CSV file of different URLs. I am keepin…
Python Pandas merge only certain columns
Is it possible to only merge some columns? I have a DataFrame df1 with columns x, y, z, and df2 with columns x, a ,b, c, d, e, f, etc. I want to merge the two DataFrames on x, but I only want to merge columns df2.a, df2.b – not the entire DataFrame. The result would be a DataFrame with