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Use cases for the 'setdefault' dict method
...e case: Grouping items (in unsorted data, else use itertools.groupby)
# really verbose
new = {}
for (key, value) in data:
if key in new:
new[key].append( value )
else:
new[key] = [value]
# easy with setdefault
new = {}
for (key, value) in data:
group = new.setdefault(k...
When is “i += x” different from “i = i + x” in Python?
...
This depends entirely on the object i.
+= calls the __iadd__ method (if it exists -- falling back on __add__ if it doesn't exist) whereas + calls the __add__ method1 or the __radd__ method in a few cases2.
From an API perspective, __iadd__ is supposed to be used fo...
Timeout on a function call
I'm calling a function in Python which I know may stall and force me to restart the script.
18 Answers
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How to convert vector to array
...making a pointer that points to the actual array the vector is using internally. If you want to copy GMan's answer explains how
– Michael Mrozek
May 27 '10 at 17:22
4
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Programmatically Request Access to Contacts
...ss to the address book must be granted before it can be access programmatically. Here is what I ended up doing.
#import <AddressBookUI/AddressBookUI.h>
// Request authorization to Address Book
ABAddressBookRef addressBookRef = ABAddressBookCreateWithOptions(NULL, NULL);
if (ABAddress...
Why do we always prefer using parameters in SQL statements?
...uld be
SELECT empSalary from employee where salary = 0 or 1=1
whereby all empSalaries would be returned.
Further, a user could perform far worse commands against your database, including deleting it If they wrote 0; Drop Table employee:
SELECT empSalary from employee where salary = 0; Drop Ta...
Remove a folder from git tracking
...elopment environment)?
Answer
Step 1. Add the folder path to your repo's root .gitignore file.
path_to_your_folder/
Step 2. Remove the folder from your local git tracking, but keep it on your disk.
git rm -r --cached path_to_your_folder/
Step 3. Push your changes to your git repo.
The folde...
python exception message capturing
...work, I get syntax error, what is the proper way of doing this for logging all kind of exceptions to a file
11 Answers
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How do you query for “is not null” in Mongo?
...
This will return all documents with a key called "IMAGE URL", but they may still have a null value.
db.mycollection.find({"IMAGE URL":{$exists:true}});
This will return all documents with both a key called "IMAGE URL" and a non-null value.
d...
Assignment inside lambda expression in Python
I have a list of objects and I want to remove all objects that are empty except for one, using filter and a lambda expression.
...