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How to reshape data from long to wide format
...mes(df) <- unique(dat1$name)
df
sqldf package:
library(sqldf)
sqldf('SELECT name,
MAX(CASE WHEN numbers = 1 THEN value ELSE NULL END) x1,
MAX(CASE WHEN numbers = 2 THEN value ELSE NULL END) x2,
MAX(CASE WHEN numbers = 3 THEN value ELSE NULL END) x3,
MAX(CASE WHEN numbe...
MySQL: What's the difference between float and double?
...INSERT INTO `test` values (1.2,1.2,1.2,1.2);
The table showing like this:
SELECT * FROM `test`;
+------+------+------+------+
| fla | flb | dba | dbb |
+------+------+------+------+
| 1.2 | 1.2 | 1.20 | 1.20 |
+------+------+------+------+
See the difference?
We try to next example:
SELECT ...
Why does SSL handshake give 'Could not generate DH keypair' exception?
...DHE_.... The later would happen if I added BouncyCastle. If TLS_ECDHE_ was selected, MOST OF the time it worked, but not ALWAYS, so adding even BouncyCastle provider was unreliable (failed with same error, every other time or so). I guess somewhere in the Sun SSL implementation sometimes it choose D...
Replacement for “rename” in dplyr
...
The next version of dplyr will support an improved version of select that also incorporates renaming:
> mtcars2 <- select( mtcars, disp2 = disp )
> head( mtcars2 )
disp2
Mazda RX4 160
Mazda RX4 Wag 160
Datsun 710 108
Hornet 4 Drive 258
H...
MongoDB仿关系型数据库Group聚合例子 - 大数据 & AI - 清泛网 - 专注C/C++及内核技术
...系型数据库例子，通过BsonJavaScript脚本实现。相当的SQL：select * from GroupDemo a right join (select userName,max(date) maxdate from GroupDemo group by userName) b on a date=b maxdate
namespace MongoGroupDemo
{
class Program
{
private static string MongoConnStr...
SQL Switch/Case in 'where' clause
...
declare @locationType varchar(50);
declare @locationID int;
SELECT column1, column2
FROM viewWhatever
WHERE
@locationID =
CASE @locationType
WHEN 'location' THEN account_location
WHEN 'area' THEN xxx_location_area
WHEN 'division' THEN xxx_location_division
END...
Which kind of pointer do I use when?
...covariant return and non-owning. A rewrite might be good if you meant the union rather than intersection. I'd also say that iteration is worth special mention also.
– Ben Voigt
Jan 2 '12 at 23:11
...
Entity Framework - Include Multiple Levels of Properties
...
For EF 6
using System.Data.Entity;
query.Include(x => x.Collection.Select(y => y.Property))
Make sure to add using System.Data.Entity; to get the version of Include that takes in a lambda.
For EF Core
Use the new method ThenInclude
query.Include(x => x.Collection)
.ThenIncl...
Making a UITableView scroll when text field is selected
... defaultCenter] addObserver:self
selector:@selector(keyboardWillShow:)
name:UIKeyboardWillShowNotification
object:nil];
// Register notification when the keyboard will b...
Removing fields from struct or hiding them in JSON Response
...ending back to the caller. I'd now like to allow the caller to be able to select the specific fields they would like returned by passing in a "fields" GET parameter.
...