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Compare two data.frames to find the rows in data.frame 1 that are not present in data.frame 2
...ata.frame(a = 1:3, b=letters[1:3])
require(sqldf)
a1NotIna2 <- sqldf('SELECT * FROM a1 EXCEPT SELECT * FROM a2')
And the rows which are in both data frames:
a1Ina2 <- sqldf('SELECT * FROM a1 INTERSECT SELECT * FROM a2')
The new version of dplyr has a function, anti_join, for exactly the...
What are the various “Build action” settings in Visual Studio project properties and what do they do
... as a default... I'm referring to the BuildAction property for each file selected in Solution Explorer. There are a number of options and it's difficult to know what each one of them will do.
...
Manually put files to Android emulator SD card
... Card through the Android Perspective (it is called DDMS in Eclipse). Just select the Emulator in the left part of the screen and then choose the File Explorer tab. Above the list with your files should be two symbols, one with an arrow pointing at a phone, clicking this will allow you to choose a f...
What does an Asterisk (*) do in a CSS selector?
...
It is a wildcard, this means it will select all elements within that portion of the DOM.
For example, if I want apply margin to every element on my entire page you can use:
* {
margin: 10px;
}
You can also use this within sub-selections, for example the ...
When and why are database joins expensive?
...s back to mitigating the size of the working set. Joins involving properly selected keys with correctly set up indexes are cheap, not expensive, because they allow significant pruning of the result before the rows are materialised.
Materialising the result involves bulk disk reads which are the mo...
Failed to build gem native extension (installing Compass)
...l the Xcode Command Line Tools this is the key to install Compass.
xcode-select --install
Installing the Xcode Command Line Tools are the key to getting Compass working on OS X
3. Install Compass
sudo gem install compass
...
Delete sql rows where IDs do not have a match from another table
...HERE f.id IS NULL
Using NOT EXISTS:
DELETE FROM BLOB
WHERE NOT EXISTS(SELECT NULL
FROM FILES f
WHERE f.id = fileid)
Using NOT IN:
DELETE FROM BLOB
WHERE fileid NOT IN (SELECT f.id
FROM FILES f)
Warning
Whenever possible, per...
“Unable to find manifest signing certificate in the certificate store” - even when add new key
...t click on your project
click on properties
usually on the left-hand side, select the "Signing" tab
check off the Sign the ClickOnce manifests
Make sure you save!
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How to comment out a block of code in Python [duplicate]
...
vim with nerdcommenter. Select the block you want and ,c<space>
– dev_nut
Oct 10 '14 at 22:37
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Webstorm: “Cannot Resolve Directory”
...t directory as a Resource. To do this, go to Settings > Directories and select your asset root folder from the right-hand panel. Then mark it as Resource Root by clicking the button above the file browser.
From the Jetbrains documentation, a Resource Root enables WebStorm to complete relative pa...