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Determine the data types of a data frame's columns
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Your best bet to start is to use ?str(). To explore some examples, let's make some data:
set.seed(3221) # this makes the example exactly reproducible
my.data <- data.frame(y=rnorm(5),
x1=c(1:5),
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Writing files in Node.js
I've been trying to find a way to write to a file when using Node.js, but with no success. How can I do that?
19 Answers
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(this == null) in C#!
Due to a bug that was fixed in C# 4, the following program prints true . (Try it in LINQPad)
6 Answers
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jQuery SVG, why can't I addClass?
I am using jQuery SVG. I can't add or remove a class to an object. Anyone know my mistake?
15 Answers
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Browse and display files in a git repo without cloning
Is there a way to browse and display files in a git repo without cloning it first? I can do those in svn using the commands:
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How to DROP multiple columns with a single ALTER TABLE statement in SQL Server?
...ike to write a single SQL command to drop multiple columns from a single table in one ALTER TABLE statement.
11 Answers
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What does the “map” method do in Ruby?
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The map method takes an enumerable object and a block, and runs the block for each element, outputting each returned value from the block (the original object is unchanged unless you use map!):
[1, 2, 3].map { |n| n * n } #=> [1, 4, 9]
Array and Rang...
Python memoising/deferred lookup property decorator
Recently I've gone through an existing code base containing many classes where instance attributes reflect values stored in a database. I've refactored a lot of these attributes to have their database lookups be deferred, ie. not be initialised in the constructor but only upon first read. These attr...
Get selected subcommand with argparse
When I use subcommands with python argparse, I can get the selected arguments.
2 Answers
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How do I associate a Vagrant project directory with an existing VirtualBox VM?
Somehow my Vagrant project has disassociated itself from its VirtualBox VM, so that when I vagrant up Vagrant will import the base-box and create a new virtual machine.
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