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How to Correctly Use Lists in R?
...dresses the question of the difference between [] and [[]].
In short [[]] selects a single item from a list and [] returns a list of the selected items. In your example, x = list(1, 2, 3, 4)' item 1 is a single integer but x[[1]] returns a single 1 and x[1] returns a list with only one value.
>...
Install Gem from Github Branch?
...file.5.html#GIT
Update: There's a github source identifier.
gem 'country_select', github: 'stefanpenner/country_select'
However, they warn against using it: NOTE: This shorthand should be avoided until Bundler 2.0, since it currently expands to an insecure git:// URL. This allows a man-in-the-mi...
What is this 'Lambda' everyone keeps speaking of?
... without bloating your code unnecessarily. For example, in Ruby:
(1..100).select {|num| num % 2 == 0}
This will create an array containing the even numbers between 1 and 100. We don't have to write out an explicit loop — the select method takes a function that it uses to test the values, so all...
Rails where condition using NOT NIL
..., so you really should just use the joins predicate:
Foo.joins(:bar)
Select * from Foo Inner Join Bars ...
But, for the record, if you want a "NOT NULL" condition simply use the not predicate:
Foo.includes(:bar).where.not(bars: {id: nil})
Select * from Foo Left Outer Join Bars on .. WHERE ...
Google Maps API 3 - Custom marker color for default (dot) marker
...he Path menu.
To move the path to the (0,0), go to the Path Edit mode (F2) select all
the control nodes and drag them. Moving the object with F1, won't change the path node coords.
To ensure the reference point is at (0,0), you can select it alone and edit the coords by hand on the top toolbar.
Afte...
How to map a composite key with JPA and Hibernate?
... way you write queries (making them more or less verbose):
with IdClass
select t.levelStation from Time t
with EmbeddedId
select t.timePK.levelStation from Time t
References
JPA 1.0 specification
Section 2.1.4 "Primary Keys and Entity Identity"
Section 9.1.14 "EmbeddedId Annotation"
Sect...
How can I turn a List of Lists into a List in Java 8?
... .collect(Collectors.toList())
This is would be similar in SQL to having SELECT statements within SELECT statements.
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How do I add more members to my ENUM-type column in MySQL?
... do not appear in your ENUM. What is the output of the following command?
SELECT DISTINCT country FROM carmake;
ANOTHER EDIT: What is the output of the following command?
SHOW VARIABLES LIKE 'sql_mode';
Is it STRICT_TRANS_TABLES or STRICT_ALL_TABLES? That could lead to an error, rather than the ...
Weighted random numbers
...
if you have a bag of red and blue marbles and you select a red marble from it and don't replace it is the probability of selecting another red marble still the same? In the same way, your statement "Pick elements from the bag sequentially until it is empty" produces a totall...
How do I create a unique constraint that also allows nulls?
...dy found separately in other, properly defined columns. It should never be selected or used.
So, my story is that this is not a surrogate NULL, and I'm sticking to it! Since we don't actually want the non-NULL value for any purpose other than to trick the UNIQUE index to ignore NULLs, our use case ...