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Summarizing multiple columns with dplyr? [duplicate]

I'm struggling a bit with the dplyr-syntax. I have a data frame with different variables and one grouping variable. Now I want to calculate the mean for each column within each group, using dplyr in R. ...
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HMAC-SHA1 in bash

Is there a bash script to generate a HMAC-SHA1 hash? 4 Answers 4 ...
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Node: log in a file instead of the console

Can I configure console.log so that the logs are written on a file instead of being printed in the console? 19 Answers ...
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What are Aggregates and PODs and how/why are they special?

This FAQ is about Aggregates and PODs and covers the following material: 6 Answers 6...
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Case-insensitive string comparison in C++ [closed]

What is the best way of doing case-insensitive string comparison in C++ without transforming a string to all uppercase or all lowercase? ...
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Pandas timeseries plot setting x-axis major and minor ticks and labels

I want to be able to set the major and minor xticks and their labels for a time series graph plotted from a Pandas time series object. ...
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How to check if a String contains another String in a case insensitive manner in Java?

Say I have two strings, 19 Answers 19 ...
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Remove rows with all or some NAs (missing values) in data.frame

I'd like to remove the lines in this data frame that: 16 Answers 16 ...
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Passing a std::array of unknown size to a function

In C++11, how would I go about writing a function (or method) that takes a std::array of known type but unknown size? 6 Ans...
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Write lines of text to a file in R

In the R scripting language, how do I write lines of text, e.g. the following two lines 13 Answers ...