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Group by multiple columns in dplyr, using string vector input
...cumentation here). This lets you use the same functions you would use with select, like so:
data = data.frame(
asihckhdoydkhxiydfgfTgdsx = sample(LETTERS[1:3], 100, replace=TRUE),
a30mvxigxkghc5cdsvxvyv0ja = sample(LETTERS[1:3], 100, replace=TRUE),
value = rnorm(100)
)
# get the column...
How to split data into training/testing sets using sample function
...101) # Set Seed so that same sample can be reproduced in future also
# Now Selecting 75% of data as sample from total 'n' rows of the data
sample <- sample.int(n = nrow(data), size = floor(.75*nrow(data)), replace = F)
train <- data[sample, ]
test <- data[-sample, ]
By using caTools pa...
Are there any side effects of returning from inside a using() statement?
...nCreated descending
where t.Id == singleId
select t).SingleOrDefault();
}
}
Indeed, I might even be tempted to use dot notation, and put the Where condition within the SingleOrDefault:
public static Transaction GetMostRecentTransaction(int singleId)
{
using...
'Microsoft.ACE.OLEDB.12.0' provider is not registered on the local machine
...bit shell:
(New-Object system.data.oledb.oledbenumerator).GetElements() | select SOURCES_NAME, SOURCES_DESCRIPTION
and you will see which provider your system can use
the long story:
the strings can be found with http://live.sysinternals.com/strings.exe
eg. on a 64bit System with 32bit drivers...
Cutting the videos based on start and end time using ffmpeg
...this answer if you don't need to trim at an exact milisecond, thus it will select the closest keyframe available. That's why it's so fast, it selects the closest keyframes and takes the snippet out without the need of reencoding. However, if you do need a precise time, taking the nearest keyframe is...
Best way to store time (hh:mm) in a database
...t a glance and performing calculations on them are straightforward.
E.g.
SELECT DATEDIFF(MINUTE, event_start, event_end)
ISO8601 date standard
If using SQLite then you don't have this, so instead use a Text field and store it in ISO8601 format eg.
"2013-01-27T12:30:00+0000"
Notes:
This use...
Changing the resolution of a VNC session in linux [closed]
... a solution using TigerVNC which is the default these days.
xrandr allows selecting the display modes (a.k.a resolutions) however
due to modelines being hard
coded
any additional modeline such as "2560x1600" or "1600x900" would need to
be added into the
code. I
think the developers who wrote the co...
Is there a timeout for idle PostgreSQL connections?
...ement an idle connection reaper. Have a cron job run something like this:
SELECT pg_terminate_backend(pid)
FROM pg_stat_activity
WHERE datname = 'regress'
AND pid <> pg_backend_pid()
AND state = 'idle'
AND state_change < current_timestamp - INTERVAL '5' MINUTE;
...
Xcode 4 - slow performance
...sure Xcode isn't open. Now find your project file. Right-click on it, and select Show Package Contents.
Next, delete project.xcworkspace.
Open Xcode and enjoy faster performance!
Thanks to:
http://meachware.blogspot.com/2011/06/speed-up-xcode-4.html
Edit: I've gotten several comments a...
An error occurred while signing: SignTool.exe not found
...a program, right-clicking on Microsoft Visual Studio Professional 2015 and selecting Change. A Visual Studio dialog will open up. Select Modify from the set of buttons at the bottom and the above dialog will appear.
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