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How to convert a data frame column to numeric type?
... convert to numeric. I suggest that you should apply transform function in order to complete your task.
Now I'm about to demonstrate certain "conversion anomaly":
# create dummy data.frame
d <- data.frame(char = letters[1:5],
fake_char = as.character(1:5),
fac ...
How do I install a plugin for vim?
...ime files. You can see that set of directories via :set runtimepath?. In order to tell Vim to also look inside ~/.vim/vim-haml you'll want to add
set runtimepath+=$HOME/.vim/vim-haml
to your ~/.vimrc. You'll likely also want the following in your ~/.vimrc to enable all the functionality provid...
What are sessions? How do they work?
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Because HTTP is stateless, in order to associate a request to any other request, you need a way to store user data between HTTP requests.
Cookies or URL parameters ( for ex. like http://example.com/myPage?asd=lol&boo=no ) are both suitable ways to ...
Is there any advantage of using map over unordered_map in case of trivial keys?
A recent talk about unordered_map in C++ made me realize that I should use unordered_map for most cases where I used map before, because of the efficiency of lookup ( amortized O(1) vs. O(log n) ). Most times I use a map, I use either int or std::string as the key type; hence, I've got...
Java : Comparable vs Comparator [duplicate]
...ts Comparable, the compareTo method of the class is defining the "natural" ordering of that object. That method is contractually obligated (though not demanded) to be in line with other methods on that object, such as a 0 should always be returned for objects when the .equals() comparisons return t...
SQLAlchemy versioning cares about class import order
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Highly active question. Earn 10 reputation in order to answer this question. The reputation requirement helps protect this question from spam and non-answer activity.
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What does 'require: false' in Gemfile mean?
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In order to require gems in your Gemfile, you will need to call Bundler.require.
You can prevent bundler from requiring the gem with require: false, but it will still install and maintain the gem. Check this out for a more det...
how do I query sql for a latest record date for each user
... date,
value,
row_number() over(partition by username order by date desc) as rn
from
yourtable
) t
where t.rn = 1
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Algorithm to return all combinations of k elements from n
...s' (1970)
The algorithm in C...
Index of Combinations in Lexicographical Order (Buckles Algorithm 515)
You can also reference a combination by its index (in lexicographical order). Realizing that the index should be some amount of change from right to left based on the index we can construct som...
RESTful Authentication
...cated by signing the query parameters
sorted in lower-case, alphabetical order using the private credential
as the signing token. Signing should occur before URL encoding the
query string.
This technique is perhaps the more compatible with a Stateless architecture, and can also be implemente...