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Remove an entire column from a data.frame in R
Does anyone know how to remove an entire column from a data.frame in R? For example if I am given this data.frame:
6 Answer...
Can I have multiple primary keys in a single table?
...as, but I came here looking to see if I could uniquely identify a row with one of a set of keys. For instance, I would like to identify a unique user with either a username OR a userid, without needing both. I guess RB's answer of unique indexes would do the trick there.
– Burr...
How to remove “Server name” items from history of SQL Server Management Studio
...st.
Note that if you have multiple entries for a single server name (e.g. one with Windows and one with SQL Auth), you won't be able to tell which one you're deleting.
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How to escape single quotes within single quoted strings
...and (2), or between (4) and (5), the shell will interpret that string as a one long word.
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What are the performance characteristics of sqlite with very large database files? [closed]
...Single Table
I tried to insert multiple rows into a sqlite file with just one table. When the file was about 7GB (sorry I can't be specific about row counts) insertions were taking far too long. I had estimated that my test to insert all my data would take 24 hours or so, but it did not complete ev...
Definition of “downstream” and “upstream”
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In terms of source control, you're "downstream" when you copy (clone, checkout, etc) from a repository. Information flowed "downstream" to you.
When you make changes, you usually want to send them back "upstream" so they make it into that repository so that everyone pulling from the same ...
Why does one often see “null != variable” instead of “variable != null” in C#?
...@Benjol Don't forget to always supply an empty else { } clause in case someone needs to add something there later and forgets to write the else keyword themselves. (Joke)
– Jeppe Stig Nielsen
May 3 '13 at 21:42
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Catch multiple exceptions at once?
...n ex) when (ex is ... || ex is ... )
Except that I still kind of hate the one-long-line layout and would personally lay the code out like the following. I think this is as functional as it is aesthetic, since I believe it improves comprehension. Some may disagree:
catch (Exception ex) when (
e...
Can I create more than one repository for github pages?
...any way that I can create more to host multiple blogs?Am I limited to just one repository for hosting(since username.github.com can only be used once?)
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How to match “anything up until this sequence of characters” in a regular expression?
...or of regex you're using, but this will
work in any of the most popular ones that can be considered "complete".
/.+?(?=abc)/
How it works
The .+? part is the un-greedy version of .+ (one or more of
anything). When we use .+, the engine will basically match everything.
Then, if there ...