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Sample random rows in dataframe
...propriate function that would return a specified number of rows picked up randomly without replacement from a data frame in R language? Can anyone help me out?
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How to show SQL queries run in the Rails console?
... can I see the actual database queries being run so I can gain more understanding of what is happening?
6 Answers
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Generate array of all letters and digits
Using ruby, is it possible to make an array of each letter in the alphabet and 0-9 easily?
7 Answers
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Format output string, right alignment
...ew = '{:>12} {:>12} {:>12}'.format(word[0], word[1], word[2])
And here's how to do it using the old % syntax (useful for older versions of Python that don't support str.format):
line_new = '%12s %12s %12s' % (word[0], word[1], word[2])
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How do I override nested NPM dependency versions?
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When I do this, only the grunt-contrib-connect dependency and its children are installed. All my other dependencies in package.json are not installed.
– iDVB
Apr 23 '15 at 0:40
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nil detection in Go
...mpiler is pointing the error to you, you're comparing a structure instance and nil. They're not of the same type so it considers it as an invalid comparison and yells at you.
What you want to do here is to compare a pointer to your config instance to nil, which is a valid comparison. To do that you...
Reading a string with scanf
...("%s", string) is equivalent to scanf("%s", &string[0]). On the other hand, scanf("%s", &string) passes a pointer-to-char[256], but it points to the same place.
Then scanf, when processing the tail of its argument list, will try to pull out a char *. That's the Right Thing when you've passe...
Reducing the space between sections of the UITableView
.... I did already try to return 0 for -tableView:heightForFooterInSection: and -tableView:heightForHeaderInSection: but that doesn't change anything.
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Which, if any, C++ compilers do tail-recursion optimization?
...t it would work perfectly well to do tail-recursion optimization in both C and C++, yet while debugging I never seem to see a frame stack that indicates this optimization. That is kind of good, because the stack tells me how deep the recursion is. However, the optimization would be kind of nice as w...
What is the most efficient/elegant way to parse a flat table into a tree?
..., we can say that all popular SQL databases support recursive queries in standard syntax.
WITH RECURSIVE MyTree AS (
SELECT * FROM MyTable WHERE ParentId IS NULL
UNION ALL
SELECT m.* FROM MyTABLE AS m JOIN MyTree AS t ON m.ParentId = t.Id
)
SELECT * FROM MyTree;
I tested recursive que...