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Adding 'serial' to existing column in Postgres
I have a small table (~30 rows) in my Postgres 9.0 database with an integer ID field (the primary key) which currently contains unique sequential integers starting at 1, but which was not created using the 'serial' keyword.
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Find XOR of all numbers in a given range
...range [a,b] where 'a' and 'b' can be typically between 1 and 4,000,000,000 inclusive. You have to find out the XOR of all the numbers in the given range.
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Multiple commands on same line
I've been trying to find something that will let me run multiple commands on the same line in Vim, akin to using semicolons to separate commands in *nix systems or & in Windows. Is there a way to do this?
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How do I get the name of the active user via the command line in OS X?
How do I get the name of the active user via the command line in OS X?
12 Answers
12
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Split code over multiple lines in an R script
I want to split a line in an R script over multiple lines (because it is too long). How do I do that?
5 Answers
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How to redirect stderr and stdout to different files in the same line in script?
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Just add them in one line command 2>> error 1>> output
However, note that >> is for appending if the file already has data. Whereas, > will overwrite any existing data in the file.
So, command 2> error 1> outpu...
Placing Unicode character in CSS content value [duplicate]
...ter {
content: "\2193";
}
The general format for a Unicode character inside a string is \000000 to \FFFFFF – a backslash followed by six hexadecimal digits. You can leave out leading 0 digits when the Unicode character is the last character in the string or when you add a space after the Uni...
using gitignore to ignore (but not delete) files
I have a tmp directory in my git repo I'd like to still exist, but be ignored. I added it to .gitignore , but git status still tells me about changes to files in that directory. I tried git rm -r --cached , but that removes it from the remote repo. How can I stop tracking changes to this dire...
Call an activity method from a fragment
Trying to call a method in my activity from a fragment. I want the fragment to give the method data and to get the data when the method return. I want to achieve similar to call on a static method, but without the use of static because it create problems in the activity.
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Pandas: create two new columns in a dataframe with values calculated from a pre-existing column
I am working with the pandas library and I want to add two new columns to a dataframe df with n columns (n > 0).
These new columns result from the application of a function to one of the columns in the dataframe.
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