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Quickly reading very large tables as dataframes
...ahead of time, the table does not contain any column headers or row names, and does not have any pathological characters that I have to worry about.
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Why does this loop produce “warning: iteration 3u invokes undefined behavior” and output more than 4
...s no such thing as "unsigned integer overflow") means undefined behaviour. And this means anything can happen, and discussing why does it happen under the rules of C++ doesn't make sense.
C++11 draft N3337: §5.4:1
If during the evaluation of an expression, the result is not mathematically de...
What is the difference between UTF-8 and Unicode?
...
To expand on the answers others have given:
We've got lots of languages with lots of characters that computers should ideally display. Unicode assigns each character a unique number, or code point.
Computers deal with such number...
multiprocessing: sharing a large read-only object between processes?
...ng share objects created earlier in the program?"
No (python before 3.8), and Yes in 3.8 (https://docs.python.org/3/library/multiprocessing.shared_memory.html#module-multiprocessing.shared_memory)
Processes have independent memory space.
Solution 1
To make best use of a large structure with lots...
must appear in the GROUP BY clause or be used in an aggregate function
...
To workaround this issue, you must calculate the aggregate in a sub-query and then join it with itself to get the additional columns you'd need to show:
SELECT m.cname, m.wmname, t.mx
FROM (
SELECT cname, MAX(avg) AS mx
FROM makerar
GROUP BY cname
) t JOIN makerar m ON m.cname = t....
check if directory exists and delete in one command unix
Is it possible to check if a directory exists and delete if it does,in Unix using a single command? I have situation where I use ANT 'sshexec' task where I can run only a single command in the remote machine. And I need to check if directory exists and delete it...
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Git: what is a dangling commit/blob and where do they come from?
...orking with your git repository, you may end up backing out of operations, and making other moves that cause intermediary blobs, and even some things that git does for you to help avoid loss of information.
Eventually (conditionally, according to the git gc man page) it will perform garbage collect...
When should the volatile keyword be used in C#?
...od explanation of the volatile keyword in C#? Which problems does it solve and which it doesn't? In which cases will it save me the use of locking?
...
Is there an R function for finding the index of an element in a vector?
In R, I have an element x and a vector v . I want to find the first index of an element in v that is equal to x . I know that one way to do this is: which(x == v)[[1]] , but that seems excessively inefficient. Is there a more direct way to do it?
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Importing CSV with line breaks in Excel 2007
...king on the file in Explorer.
I have a CSV file that is in UTF-8 encoding and contains newlines in some cells. If I open this file from Excel's File->Open menu, the "import CSV" wizard pops up and the file cannot be correctly imported: the newlines start a new row even when quoted. If I open thi...