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Rails find_or_create_by more than one attribute?
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edited Jan 17 '17 at 12:26
Deepak Mahakale
18.4k77 gold badges5454 silver badges7373 bronze badges
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What's the difference between dist-packages and site-packages?
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edited Sep 18 '12 at 14:28
answered Feb 22 '12 at 1:52
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ERROR: permission denied for sequence cities_id_seq using Postgres
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edited Apr 13 '17 at 12:26
simbo1905
4,69811 gold badge3838 silver badges6666 bronze badges
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MySQL show current connection info
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189
There are MYSQL functions you can use. Like this one that resolves the user:
SELECT USER();
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Using bitwise OR 0 to floor a number
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163
How does it work? Our theory was that using such an operator casts the
number to an integ...
Indentation in Go: tabs or spaces?
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197
The official recommendation is formatting your code with
go fmt
or using the gofmt command ...
How to create a unique index on a NULL column?
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answered Oct 10 '08 at 14:17
willasaywhatwillasaywhat
2,3682020 silver badges2323 bronze badges
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Drop data frame columns by name
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You can use a simple list of names :
DF <- data.frame(
x=1:10,
y=10:1,
z=rep(5,10),
a=11:20
)
drops <- c("x","z")
DF[ , !(names(DF) %in% drops)]
Or, alternatively, you can make a list of those to keep and refer to them by name :
keeps <- c("y", "a")
DF[keeps]
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Turning off some legends in a ggplot
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edited Dec 25 '15 at 20:47
answered Jan 30 '13 at 12:55
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Record file copy operation with Git
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114
Git does not do rename tracking nor copy tracking, which means it doesn't record renames or co...