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What is causing ERROR: there is no unique constraint matching given keys for referenced table?
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why isn't the declared PK considered as a unique constraint ? it's not like you can have a nonunique PK...
– amphibient
Sep 7 '16 at 18:14
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Pandas every nth row
... c
0 x x x
1 x x x
2 x x x
The index is floor-divved by the stride (2, in this case). If the index is non-numeric, instead do
# df.groupby(np.arange(len(df)) // 2).first()
df.groupby(pd.RangeIndex(len(df)) // 2).first()
a b c
0 x x x
1 x x x
2 x x x
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Is #pragma once part of the C++11 standard?
Traditionally, the standard and portable way to avoid multiple header inclusions in C++ was/is to use the #ifndef - #define - #endif pre-compiler directives scheme also called macro-guard scheme (see code snippet below).
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Get first key in a (possibly) associative array?
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As a side note, reset() also happens to return the first element (value, not key) of any array, which can be handy as well.
– devios1
Aug 21 '12 at 22:14
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How to make Google Chrome JavaScript console persistent?
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For anyone else that didn't no where Developer Tools > Settings are: when you've got the console open there's a cog in the bottom right of the screen, the "Preserve log upon navigation" is on the first tab in the Console section.
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What do the &,
...ow me to quote the YAML spec here:
Repeated nodes (objects) are first identified by an anchor (marked with the ampersand - “&”), and are then aliased (referenced with an asterisk - “*”) thereafter.
So parts of your example
development: &default
adapter: postgresql
databas...
What is a stored procedure?
...ood first step against SQL injection.
Stored procedures do come with downsides, basically the maintenance associated with your basic CRUD operation. Let's say for each table you have an Insert, Update, Delete and at least one select based on the primary key, that means each table will have 4 proced...
Why does javascript map function return undefined?
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Ahh...I did not know there was a filter function.Thanks.
– Akshat Jiwan Sharma
Apr 16 '13 at 12:31
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Read user input inside a loop
...dev/tty
more info: http://compgroups.net/comp.unix.shell/Fixing-stdin-inside-a-redirected-loop
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Aligning rotated xticklabels with their respective xticks
...e below. If you imagine a rectangular box around the rotated label, which side of the rectangle do you want to be aligned with the tickpoint?
Given your description, you want: ha='right'
n=5
x = np.arange(n)
y = np.sin(np.linspace(-3,3,n))
xlabels = ['Ticklabel %i' % i for i in range(n)]
fig, ax...