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How do I loop through a list by twos? [duplicate]
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You can also use this syntax (L[start:stop:step]):
mylist = [1,2,3,4,5,6,7,8,9,10]
for i in mylist[::2]:
print i,
# prints 1 3 5 7 9
for i in mylist[1::2]:
print i,
# prints 2 4 6 8 10
Where the first digit is the starting index (defaults to beginning of list or 0)...
PostgreSQL return result set as JSON array?
...M t
or combine json_agg with a cast:
SELECT json_agg(t)::jsonb FROM t
My testing suggests that aggregating them into an array first is a little faster. I suspect that this is because the cast has to parse the entire JSON result.
9.2
9.2 does not have the json_agg or to_json functions, so you ...
Android: Generate random color on click?
...ch I am programmaticly creating drawables and presenting them to the user. My goal is to click on said ImageView and change the drawable's color.
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Detect when browser receives file download
...ment.cookies does not include the downloadToken, check the cookie path. In my case, I had to set the path to "/" on server side (e.g. cookie.setPath("/") in Java) even though path was blank by default. For some time I thought the issue was the special 'localhost' domain cookie handling (stackoverflo...
When to dispose CancellationTokenSource?
...ssary to call Dispose on CancellationTokenSource... I had a memory leak in my project and it turned out that CancellationTokenSource was the problem.
My project has a service, that is constantly reading database and fires off different tasks, and I was passing linked cancellation tokens to my worke...
Visual Studio jump to next error shortcut?
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F8 (and Shift+F8 to go backwards).
Or at least that's what it is in my keyboard profile - you can go to tools\options\environment\keyboard and check out Edit.GoToNextLocation.
Note If you configured Visual Studio using VB keyboard settings, no key has been assigned to this function. You need...
How to get HTTP response code for a URL in Java?
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In my specific case and with your method, I get an IOException ("Failed to authenticate with proxy") which is usually an http error 407. Is there a way where I can get a precision (the http error code) about the exception raised...
Android on-screen keyboard auto popping up
One of my apps has an "opening screen" (basically a menu) that has an EditText followed by several Button s. The problem is that several of my users are reporting that when they open the app it's automatically popping up the on-screen keyboard without them even touching the EditText . As far as ...
Sass Variable in CSS calc() function
... calc() function in a Sass stylesheet, but I'm having some issues. Here's my code:
7 Answers
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MySQL Cannot drop index needed in a foreign key constraint
I need to ALTER my existing database to add a column. Consequently I also want to update the UNIQUE field to encompass that new column. I'm trying to remove the current index but keep getting the error MySQL Cannot drop index needed in a foreign key constraint
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