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Find difference between timestamps in seconds in PostgreSQL
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Try:
SELECT EXTRACT(EPOCH FROM (timestamp_B - timestamp_A))
FROM TableA
Details here: EXTRACT.
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Python in Xcode 4+?
...d it out! The steps make it look like it will take more effort than it actually does.
These instructions are for creating a project from scratch. If you have existing Python scripts that you wish to include in this project, you will obviously need to slightly deviate from these instructions.
If yo...
Twitter image encoding challenge [closed]
... 4 = 64 colors) that simply gets blended in in some proportion. Mathematically, this is equivalent to a variable brightness and constant contrast adjustment for each color. Unfortunately, it also means there's no negative contrast to flip the colors.
Once it's computed the position, orientation a...
Get free disk space
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I know this answer is ancient, but you usually need to use AvailableFreeSpace as @knocte says. AvailableFreeSpace lists how much is actually available for the user (due to quotos). TotalFreeSpace lists what is available on the disk, irregardless of what the user can ...
Pandas: drop a level from a multi-level column index?
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@yoonghm It is there, you are probably just calling it on columns that don't have a multi-index
– matt harrison
Dec 18 '18 at 14:59
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CSS: Change image src on img:hover
... <img src="https://cdn4.iconfinder.com/data/icons/imoticons/105/imoticon_15-128.png" />
<img src="https://cdn4.iconfinder.com/data/icons/imoticons/105/imoticon_12-128.png" />
</a>
CSS
a img:last-child {
display: none;
}
a:hover img:last-child {
display: block;
}
a:ho...
Set variable in jinja
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Nice shorthand for Multiple variable assignments
{% set label_cls, field_cls = "col-md-7", "col-md-3" %}
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How to get the difference between two arrays in JavaScript?
... The fastest way is the most obviously naive solution. I tested all of the proposed solutions for symmetric diff in this thread, and the winner is: function diff2(a, b) { var i, la = a.length, lb = b.length, res = []; if (!la) return b; else if (!lb) r...
What is the difference between GitHub and gist?
... A repository is for user-created files. A gist is for a piece of code (usually unconnected to other code), like for discussing or giving examples.
– Kerrek SB
Jul 3 '13 at 8:01
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Regex (grep) for multi-line search needed [duplicate]
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Without the need to install the grep variant pcregrep, you can do multiline search with grep.
$ grep -Pzo "(?s)^(\s*)\N*main.*?{.*?^\1}" *.c
Explanation:
-P activate perl-regexp for grep (a powerful extension of regular expressions)
-z suppress...