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How do I delete rows in a data frame?
...
The key idea is you form a set of the rows you want to remove, and keep the complement of that set.
In R, the complement of a set is given by the '-' operator.
So, assuming the data.frame is called myData:
myData[-c(2, 4, 6), ] # notice the -
Of...
Is it possible to print a variable's type in standard C++?
...ich can turn an expression into a type. And decltype() comes with its own set of very interesting rules. For example decltype(a) and decltype((a)) will generally be different types (and for good and understandable reasons once those reasons are exposed).
Will our trusty typeid(a).name() help us e...
Listing only directories using ls in Bash?
...ers. To include them, either specify them explicitly like ls -d .*/ */, or set the dotglob option in Bash.
– Gergő
Jan 11 '15 at 15:15
1
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Multiple arguments to function called by pthread_create()?
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Obfuscated C Code Contest 2006. Please explain sykes2.c
...2 (a space) or character 33 (a !). The first table (">'txiZ^(~z?") is a set of 10 bitmaps describing the appearance of each character, and the second table (";;;====~$::199") selects the appropriate bit to display from the bitmap.
The second table
Let's start by examining the second table, int ...
Directory-tree listing in Python
How do I get a list of all files (and directories) in a given directory in Python?
20 Answers
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Useful code which uses reduce()? [closed]
...ster for large lists. timeit.repeat('int("".join(map(str, digit_list)))', setup = 'digit_list = list(d%10 for d in xrange(1,1000))', number=1000) takes ~0.09 seconds while timeit.repeat('reduce(lambda a,d: 10*a+d, digit_list)', setup = 'digit_list = list(d%10 for d in xrange(1,1000))', number=1000)...
Java - escape string to prevent SQL injection
...ction conn = null;
PreparedStatement stmt = null;
try {
conn = setupTheDatabaseConnectionSomehow();
stmt = conn.prepareStatement("INSERT INTO person (name, email) values (?, ?)");
stmt.setString(1, name);
stmt.setString(2, email);
stmt.executeUpdate();
}
fin...
How to get the last N records in mongodb?
... Natural order should not be relied upon; if you are using a replica set (and you should be), different nodes might well have the same documents stored in a different order on disk.
– Vince Bowdren
Feb 10 '17 at 16:46
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How to split() a delimited string to a List
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