大约有 43,083 项符合查询结果（耗时：0.0434秒） [XML]
Count number of rows within each group
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14 Answers
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Bash conditionals: how to “and” expressions? (if [ ! -z $VAR && -e $VAR ])
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edited Dec 22 '14 at 22:36
answered Jan 19 '12 at 2:16
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Jquery select all elements that have $jquery.data()
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edited Jul 9 '15 at 6:42
Tushar
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Reasons for using the set.seed function
...produce as I just asked for something "random":
R> sample(LETTERS, 5)
[1] "K" "N" "R" "Z" "G"
R> sample(LETTERS, 5)
[1] "L" "P" "J" "E" "D"
These two, however, are identical because I set the seed:
R> set.seed(42); sample(LETTERS, 5)
[1] "X" "Z" "G" "T" "O"
R> set.seed(42); sample(LE...
Regex to match a digit two or four times
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145
There's no specific syntax for that, but there are lots of ways to do it:
(?:\d{4}|\d{2}) ...
How to achieve function overloading in C?
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14 Answers
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python: Change the scripts working directory to the script's own directory
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edited Feb 10 '12 at 14:41
answered Sep 16 '09 at 13:26
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Can JSON start with “[”?
...teral names.
A JSON text is a serialized object or array.
Update (2014)
As of March 2014, there is a new JSON RFC (7159) that modifies the definition slightly (see pages 4/5).
The definition per RFC 4627 was: JSON-text = object / array
This has been changed in RFC 7159 to: JSON-text = ws v...
Skip a submodule during a Maven build
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149
Sure, this can be done using profiles. You can do something like the following in your parent...