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Cannot ping AWS EC2 instance
...ICMP rule
Protocol: Echo Request
Port: N/A
Source: your choice (I would select Anywhere to be able to ping from any machine)
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Extracting specific columns from a data frame
...r package, if your data.frame is called df1:
library(dplyr)
df1 %>%
select(A, B, E)
This can also be written without the %>% pipe as:
select(df1, A, B, E)
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EOL conversion in notepad ++
...That functionality is already built into Notepad++. From the "Edit" menu, select "EOL Conversion" -> "UNIX/OSX Format".
screenshot of the option for even quicker finding (or different language versions)
You can also set the default EOL in notepad++ via "Settings" -> "Preferences" -> "New...
Using column alias in WHERE clause of MySQL query produces an error
... though, by putting the expression directly into the WHERE x IN y clause:
SELECT `users`.`first_name`,`users`.`last_name`,`users`.`email`,SUBSTRING(`locations`.`raw`,-6,4) AS `guaranteed_postcode`
FROM `users` LEFT OUTER JOIN `locations`
ON `users`.`id` = `locations`.`user_id`
WHERE SUBSTRING(`loca...
Directive isolate scope with ng-repeat scope in AngularJS
...moved:
<li ng-repeat="name in names"
ng-class="{ active: $index == selected }"
ng-click="selected = $index">
{{$index}}: {{name.first}} {{name.last}}
</li>
Here is a JSFiddle demonstrating that it won't work. You get the exact same results as in your directive.
Why doesn'...
TCP vs UDP on video stream
...s clients is long due to the singularity of the event. Pre-recorded video-casts typically don't have as much of a problem with this because viewers stagger their replay activity; therefore TCP is more appropriate for replaying a video-on-demand.
IP multicast significantly reduces video bandwidth re...
How do you add Boost libraries in CMakeLists.txt?
...on't need to specify components for header only libraries, such as lexical_cast. Thus you only need the find_package and include_directories command.
– miguel.martin
May 13 '15 at 13:13
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How can I select an element with multiple classes in jQuery?
I want to select all the elements that have the two classes a and b .
13 Answers
13...
String.Join method that ignores empty strings?
... simpler, since you can do it in SQL directly:
PostgreSQL & MySQL:
SELECT
concat_ws(' / '
, NULLIF(searchTerm1, '')
, NULLIF(searchTerm2, '')
, NULLIF(searchTerm3, '')
, NULLIF(searchTerm4, '')
) AS RPT_SearchTerms;
And even with the glorious MS-SQ...
Why does MYSQL higher LIMIT offset slow the query down?
...h more than 16 million records [2GB in size]. The higher LIMIT offset with SELECT, the slower the query becomes, when using ORDER BY *primary_key*
...