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Remove an entire column from a data.frame in R
...=4:6)
to remove just the a column you could do
Data <- subset( Data, select = -a )
and to remove the b and d columns you could do
Data <- subset( Data, select = -c(d, b ) )
You can remove all columns between d and b with:
Data <- subset( Data, select = -c( d : b )
As I said above...
Error when trying to obtain a certificate: The specified item could not be found in the keychain
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I solved it. Ensure you are in the "Certificates" section and you select "Apple Worldwide Developer Relations Certification Authority" before requesting a certificate.
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Unknown Column In Where Clause
...om right to left. So the where clause is parsed and evaluate prior to the select clause. Because of this the aliasing of u_name to user_name has not yet occurred.
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Finding all cycles in a directed graph
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This answer is much better than the answer selected. I struggled for quite a while trying to figure out how to get all simple cycles from the strongly connected components. It turns out this is non-trivial. The paper by Johnson contains a great algorithm, but is a lit...
Find CRLF in Notepad++
...h processes:
Simple search (Ctrl+F), Search Mode = Normal
You can select an EOL in the editing window.
Just move the cursor to the end of the line, and type Shift+Right Arrow.
or, to select EOL with the mouse, start just at the line end and drag to the start of the next line; dr...
When to Redis? When to MongoDB? [closed]
...e, writing stupid sql statements... not just one but freaking everywhere. "select this, select that". But in particular you remember the irritating WHERE clause. Where lastname equals "thornton" and movie equals "bad santa." Urgh. You think, "why don’t those dbas just do their job and give me som...
How to comment and uncomment blocks of code in the Office VBA Editor
...tor, go to View, Toolbars, Customise... or right click on the tool bar and select Customise...
Under the Commands tab, select the Edit menu on the left.
Then approximately two thirds of the way down there's two icons, Comment Block and Uncomment Block.
Drag and drop these onto your toolbar and th...
Shell脚本编程30分钟入门 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...h
. $real_path
用户输入
执行脚本时传入脚本运行中输入select菜单stdin和stdout
常用的命令
sh脚本结合系统命令便有了强大的威力，在字符处理领域，有grep、awk、sed三剑客，grep负责找出特定的行，awk能将行拆分成多个字段，s...
Xcode stuck at “Your application is being uploaded”
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@Andru: you can select mysticboy59's answer as correct so this topic will be closed. He did put some effort into it.
– Rok Jarc
Nov 15 '13 at 9:11
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PostgreSQL function for last inserted ID
...e:
INSERT INTO persons (lastname,firstname) VALUES ('Smith', 'John');
SELECT currval('persons_id_seq');
The name of the sequence must be known, it's really arbitrary; in this example we assume that the table persons has an id column created with the SERIAL pseudo-type. To avoid relying on thi...