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How can I profile Python code line-by-line?
I've been using cProfile to profile my code, and it's been working great. I also use gprof2dot.py to visualize the results (makes it a little clearer).
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How to select the first element with a specific attribute using XPath
...n 17 '09 at 10:48
Jonathan FinglandJonathan Fingland
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Disabling Chrome cache for website development
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The Chrome DevTools can disable the cache.
Right-click and choose Inspect Element to open the DevTools. Or use one of the following keyboard shortcuts:
F12
Command+Option+i on Mac
Control+Shift+i on Windows or Linux
Click Network in the toolbar to open the network pane.
Check ...
Using LIMIT within GROUP BY to get N results per group?
...T aggregated function to get all years into a single column, grouped by id and ordered by rate:
SELECT id, GROUP_CONCAT(year ORDER BY rate DESC) grouped_year
FROM yourtable
GROUP BY id
Result:
-----------------------------------------------------------
| ID | GROUPED_YEAR ...
What's the simplest way to test whether a number is a power of 2 in C++?
...will want to check for it explicitly.
http://www.graphics.stanford.edu/~seander/bithacks.html has a large collection of clever bit-twiddling algorithms, including this one.
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Are soft deletes a good idea? [duplicate]
... to include a WHERE IsDeleted = false clause in every query on this table (and so much worse if you're JOINing these tables). A mistake here would be caught as soon as a user or tester noticed a deleted record showing up again, which might take some time. Also, it would be easy for a developer to ...
How to find the kth largest element in an unsorted array of length n in O(n)?
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This is called finding the k-th order statistic. There's a very simple randomized algorithm (called quickselect) taking O(n) average time, O(n^2) worst case time, and a pretty complicated non-randomized algorithm (called introselect) taking O(n) worst case time. There's some info on Wikipedia, bu...
What is an idempotent operation?
...g that x in the mathematical definition represents the state of an object, and f is an operation that may mutate that object. For example, consider the Python set and its discard method. The discard method removes an element from a set, and does nothing if the element does not exist. So:
my_set.dis...
Mathematical functions in Swift
...an import only Darwin.
import Darwin
If you want mathematical functions and other standard classes and functions. You can import Foundation.
import Foundation
If you want everything and also classes for user interface, it depends if your playground is for OS X or iOS.
For OS X, you need impor...
Calculating the difference between two Java date instances
I'm using Java's java.util.Date class in Scala and want to compare a Date object and the current time. I know I can calculate the delta by using getTime():
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