大约有 48,000 项符合查询结果（耗时：0.0455秒） [XML]
data.table vs dplyr: can one do something well the other can't or does poorly?
... ## data.table syntax
left_join(DT2, DT1) ## dplyr syntax
# 2. select columns while join
DT1[DT2, .(z, i.mul)]
left_join(select(DT2, x, y, mul), select(DT1, x, y, z))
# 3. aggregate while join
DT1[DT2, .(sum(z) * i.mul), by = .EACHI]
DF1 %>% group_by(x, y) %>% summarise(z = su...
Peak detection in a 2D array
...\n"
Output without overlapping squares. It seems that the same areas are selected as in your example.
Some comments
The tricky part is to calculate sums of all 2x2 squares. I assumed you need all of them, so there might be some overlapping. I used slices to cut the first/last columns and rows fr...
How to show SQL queries run in the Rails console?
...ecord::Relation’s to_sql method:
User.where(:id => 3).to_sql
#=> "SELECT \"users\".* FROM \"users\" WHERE \"users\".\"id\" = 3"
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follo...
Plurality in user messages
... are wrong. The correct way of doing this is:
string message = ( noofitemsselected==1 ?
"You have selected " + noofitemsselected + " item. Are you sure you want to delete it?":
"You have selected " + noofitemsselected + " items. Are you sure you want to delete them?"
);
This is because differ...
How do I simulate a hover with a touch in touch enabled browsers?
...for added usefulness, add this to your CSS as well:
.hover {
-webkit-user-select: none;
-webkit-touch-callout: none;
}
To stop the browser asking you to copy/save/select the image or whatever.
Easy!
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How to copy from current position to the end of line in vi
...opy/paste between different instances, you can use the system clipboard by selecting the * register, so the commands become "*y$ for copying and "*p for pasting.
$ move-to-linebreak
$
y$ yank-to-linebreak
y,$
"*y$ select clipboard-register yank-to-linebreak
",*,y,$
"*p select clipboard-regist...
Comparison of full text search engine - Lucene, Sphinx, Postgresql, MySQL?
... up the firstname field as shown.
http://localhost:8983/solr/collection1/select?q=firstname:john^2&lastname:john
As you can see, firstname field is boosted up with a score of 2.
More on SolrRelevancy
searching and indexing speed
The speed is unbelievably fast and no compromise o...
Automatic Preferred Max Layout Width is not available on iOS versions prior to 8.0
... my steps below.
In xCode's Issue Navigator right click on the error and select "Reveal In Log". (Note: @Sam suggests below, look in xCode's report navigator. Also @Rivera notes in the comments that "As of Xcode 6.1.1, clicking on the warning will automatically open and highlight the conflicting l...
Android custom dropdown/popup menu
... android:paddingEnd="10dip">
<ImageView
android:id="@+id/shoe_select_icon"
android:layout_width="30dp"
android:layout_height="30dp"
android:layout_gravity="center_vertical"
android:scaleType="fitXY" />
<TextView
android:id="@+id/shoe_select_text"
android:l...
Get query from java.sql.PreparedStatement [duplicate]
...ut from above code.
Before : com.mysql.jdbc.JDBC4PreparedStatement@fa9cf: SELECT * FROM test WHERE blah1=** NOT SPECIFIED ** and blah2=** NOT SPECIFIED **
After : com.mysql.jdbc.JDBC4PreparedStatement@fa9cf: SELECT * FROM test WHERE blah1='Hello' and blah2='World'
...