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What does .SD stand for in data.table in R
... may help you see what .SD is:
DT[ , .SD[ , paste(x, v, sep="", collapse="_")], by=y]
# y V1
# 1: 1 a1_b3_c5
# 2: 3 a2_b4_c6
Basically, the by=y statement breaks the original data.table into these two sub-data.tables
DT[ , print(.SD), by=y]
# <1st sub-data.table, called '.SD' while i...
How to get the last N records in mongodb?
...d -1 will sort descending (newest to oldest.)
If you use the auto created _id field it has a date embedded in it ... so you can use that to order by ...
db.foo.find().sort({_id:1});
That will return back all your documents sorted from oldest to newest.
Natural Order
You can also use a Natura...
What are best practices for multi-language database design? [closed]
...relational table, so you get two tables, meaning (id) and word (id, meaning_id), the id in the word table represents the word id, the id in the meaning represents the meaning that is universal.
– Timo Huovinen
Sep 17 '18 at 19:27
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Is there some way to PUSH data from web server to browser?
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Yes, what you're looking for is COMET http://en.wikipedia.org/wiki/Comet_(programming). Other good Google terms to search for are AJAX-push and reverse-ajax.
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Read logcat programmatically within application
...7.
*/
public class Logger {
// http://www.java2s.com/Tutorial/Java/0040__Data-Type/SimpleDateFormat.htm
private static final String ANDROID_LOG_TIME_FORMAT = "MM-dd kk:mm:ss.SSS";
private static SimpleDateFormat logCatDate = new SimpleDateFormat(ANDROID_LOG_TIME_FORMAT);
public static Str...
Setting WPF image source in code
...packUri = "pack://application:,,,/AssemblyName;component/Images/icon.png";
_image.Source = new ImageSourceConverter().ConvertFromString(packUri) as ImageSource;
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Dealing with “java.lang.OutOfMemoryError: PermGen space” error
.../usr/share/tomcat6/bin/setenv.sh and added the following line to that: JAVA_OPTS="-Xms256m -Xmx512m -XX:+CMSClassUnloadingEnabled -XX:+CMSPermGenSweepingEnabled" - Restarted tomcat using: sudo /etc/init.d/tomcat6 start
– sami
Dec 10 '10 at 14:44
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Java equivalent to #region in C#
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With Android Studio, try this:
//region VARIABLES
private String _sMyVar1;
private String _sMyVar2;
//endregion
Careful : no blank line after //region ...
And you will get:
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How to programmatically determine the current checked out Git branch [duplicate]
...ek at contrib/completions/git-completion.bash does that for bash prompt in __git_ps1. Removing all extras like selecting how to describe detached HEAD situation, i.e. when we are on unnamed branch, it is:
branch_name="$(git symbolic-ref HEAD 2>/dev/null)" ||
branch_name="(unnamed branch)" #...
Difference between Java Enumeration and Iterator
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@Paul_Draper: Edits should not be adding new meaning to the post, that is what comments are for.
– Emil
Nov 11 '12 at 17:40
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