大约有 42,000 项符合查询结果（耗时：0.0687秒） [XML]
How to programmatically determine the current checked out Git branch [duplicate]
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edited Jun 11 '13 at 14:18
artless noise
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How to return 2 values from a Java method?
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edited May 14 '10 at 11:47
answered May 14 '10 at 7:58
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How to list the tables in a SQLite database file that was opened with ATTACH?
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edited Apr 16 '14 at 15:05
Tuan
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Difference between Java Enumeration and Iterator
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edited Aug 29 at 5:04
SusanW
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Remove empty array elements
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edited Mar 10 at 3:20
answered Sep 6 '10 at 21:10
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Drop data frame columns by name
...e to keep and refer to them by name :
keeps <- c("y", "a")
DF[keeps]
EDIT :
For those still not acquainted with the drop argument of the indexing function, if you want to keep one column as a data frame, you do:
keeps <- "y"
DF[ , keeps, drop = FALSE]
drop=TRUE (or not mentioning it) wil...
Can I use the range operator with if statement in Swift?
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edited Aug 27 '17 at 7:30
Ahmad F
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How can I extract a good quality JPEG image from a video file with ffmpeg?
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edited Sep 24 at 22:20
answered Apr 19 '12 at 18:03
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Failed to execute goal org.apache.maven.plugins:maven-surefire-plugin:2.10:test
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edited Jan 14 at 12:40
zb226
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How to check that an object is empty in PHP?
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edited Apr 5 at 1:24
answered Feb 23 '12 at 11:39
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