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How does one reorder columns in a data frame?
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Your dataframe has four columns like so df[,c(1,2,3,4)].
Note the first comma means keep all the rows, and the 1,2,3,4 refers to the columns.
To change the order as in the above question do df2[,c(1,3,2,4)]
If you want to output this file as a csv, do write.csv(df2, file="somedf.csv")
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AWS ssh access 'Permission denied (publickey)' issue [closed]
...es I've used only have the root user created by default.
See also: http://www.youtube.com/watch?v=WBro0TEAd7g
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What's the fastest way to merge/join data.frames in R?
...low we illustrate these points.
Its worthwhile to notice that the precise computation can make a huge difference on which package is fastest. For example, we do a merge and an aggregate below. We see that the results are nearly reversed for the two. In the first example from fastest to slowest w...
Get Substring - everything before certain char
I'm trying to figure out the best way to get everything before the - character in a string. Some example strings are below. The length of the string before - varies and can be any length
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When to use generic methods and when to use wild-card?
I am reading about generic methods from OracleDocGenericMethod . I am pretty confused about the comparison when it says when to use wild-card and when to use generic methods.
Quoting from the document.
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What is the difference between concurrency and parallelism?
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Concurrency is when two or more tasks can start, run, and complete in overlapping time periods. It doesn't necessarily mean they'll ever both be running at the same instant. For example, multitasking on a single-core machine.
Parallelism is when tasks literally run at the same ti...
Set the value of a variable with the result of a command in a Windows batch file
...in a Bash environment, to set the value of a variable as the result of a command, I usually do:
5 Answers
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How to disable / enable dialog negative positive buttons?
Please look at the custom dialog below. I have an edittext field on the dialog and if the text field is empty I would like to disable the positiveButton . I can get a charListener for the text field but I am not sure how I am going to set the positivebutton to disable or enable from that listene...
How to create new tmux session if none exists
I am trying to figure out how to attach to a tmux session if a named tmux session exists, if not I want to create a new one with the given name.
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How to convert comma-separated String to List?
Is there any built-in method in Java which allows us to convert comma separated String to some container (e.g array, List or Vector)? Or do I need to write custom code for that?
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