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Determine the data types of a data frame's columns
I'm using R and have loaded data into a dataframe using read.csv() . How do I determine the data type of each column in the data frame?
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Checking to see if a DateTime variable has had a value assigned
...t; (or DateTime? with the C# syntactic sugar) - make it null to start with and then assign a normal DateTime value (which will be converted appropriately). Then you can just compare with null (or use the HasValue property) to see whether a "real" value has been set.
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How do I get the first element from an IEnumerable in .net?
...often want to grab the first element of an IEnumerable<T> in .net, and I haven't found a nice way to do it. The best I've come up with is:
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curl : (1) Protocol https not supported or disabled in libcurl
...g to install the Rails environments on Ubuntu 11.04. When I launch the command rvm install 1.9.2 --with-openssl-dir=/usr/local the following error is received:
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How to install therubyracer gem on 10.10 Yosemite?
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It's also worth mentioning that if you're using a Gemfile and still having trouble installing therubyracer, it's probably because there's a different version of libv8 that's already been added to the Gemfile.lock. Just add gem 'libv8', '3.16.14.3' (or whatever is the exact version o...
Ruby: What is the easiest way to remove the first element from an array?
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Note this mutates the array and returns nil on an empty array. See drop for an alternative, as mentioned in the other answer.
– Jay
Oct 15 '15 at 21:37
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Convert string to a variable name
...ttp://www.r-bloggers.com/converting-a-string-to-a-variable-name-on-the-fly-and-vice-versa-in-r/
To convert a string to a variable:
x <- 42
eval(parse(text = "x"))
[1] 42
And the opposite:
x <- 42
deparse(substitute(x))
[1] "x"
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Writing files in Node.js
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I've tested this script using Node, and I tried changing the file path to "/home/", but I got the following error: { [Error: EACCES, open '/home/test.txt'] errno: 3, code: 'EACCES', path: '/home/test.txt' } How can I modify this script so that it will work out...
How to frame two for loops in list comprehension python
...ich they appear in traditional loop approach. Outer most loop comes first, and then the inner loops subsequently.
So, the equivalent list comprehension would be:
[entry for tag in tags for entry in entries if tag in entry]
In general, if-else statement comes before the first for loop, and if you...
What is the best way to determine the number of days in a month with JavaScript?
...ve been using this function but I'd like to know what's the most efficient and accurate way to get it.
15 Answers
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