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Determine the data types of a data frame's columns
I'm using R and have loaded data into a dataframe using read.csv() . How do I determine the data type of each column in the data frame?
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Why is `std::move` named `std::move`?
...intent of this naming is not to confuse, but rather to make your code more readable.
The history of move dates back to the original move proposal in 2002. This paper first introduces the rvalue reference, and then shows how to write a more efficient std::swap:
template <class T>
void
swap(T...
Do you use NULL or 0 (zero) for pointers in C++?
...at it is a part of the standard. It is an implementation detail as far as reading the code goes. The reader should think "NULL pointer" not "0 which in this case means NULL pointer, not a number I could be doing arithmetic with."
– Andy Lester
Mar 14 '13 at 2...
SQLAlchemy: print the actual query
...compiled to a specific dialect or engine, if the statement itself is not already bound to one you can pass this in to compile():
print(statement.compile(someengine))
or without an engine:
from sqlalchemy.dialects import postgresql
print(statement.compile(dialect=postgresql.dialect()))
When given a...
Can two applications listen to the same port?
...nother remote IP?
I know I can have one application that starts off two threads (or forks) to have similar behavior, but can two applications that have nothing in common do the same?
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What's the best way to validate an XML file against an XSD file?
...you can do something similar with SAX parser that is validating as well saxReader.setEntityResolver(your_resolver_here);
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Chrome: timeouts/interval suspended in background tabs?
...sound forces the browser to retain the performance - I discovered it after reading this comment: How to make JavaScript run at normal speed in Chrome even when tab is not active?
I need unlimited performance on-demand for a browser game that uses WebSockets, so I know from experience that using Web...
A std::map that keep track of the order of insertion?
...upposed to (ie by sorting itself as you insert), and has fast runtime. (I read this after writing my version, where I used std::list!)
– bobobobo
Oct 8 '12 at 1:16
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Swapping column values in MySQL
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As noted in MySQL docs, It's not safe to assign and read variables in a single statement. The order of operations is not guaranteed. So the only safe method is #4
– AMIB
Jan 27 '13 at 10:01
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Is errno thread-safe?
...it safe to check errno value after some calls or use perror() in multi-threaded code. Is this a thread safe variable? If not, then whats the alternative ?
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