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Group by multiple columns in dplyr, using string vector input
I'm trying to transfer my understanding of plyr into dplyr, but I can't figure out how to group by multiple columns.
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using gitignore to ignore (but not delete) files
I have a tmp directory in my git repo I'd like to still exist, but be ignored. I added it to .gitignore , but git status still tells me about changes to files in that directory. I tried git rm -r --cached , but that removes it from the remote repo. How can I stop tracking changes to this dire...
Python - write() versus writelines() and concatenated strings
...thon. I am going through the lessons and ran into a problem where I had to condense a great many target.write() into a single write() , while having a "\n" between each user input variable(the object of write() ).
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Why does base64 encoding require padding if the input length is not divisible by 3?
What is the purpose of padding in base64 encoding. The following is the extract from wikipedia:
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Difference between this and self in JavaScript
Everyone is aware of this in javascript, but there are also instances of self encountered in the wild, such as here
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Composer: how can I install another dependency without updating old ones?
I have a project with a few dependencies and I'd like to install another one, but I'd like to keep the others the way they are. So I've edited the composer.json , but if I run composer install , I get the following output:
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What is the purpose of AsQueryable()?
Is the purpose of AsQueryable() just so you can pass around an IEnumerable to methods that might expect IQueryable , or is there a useful reason to represent IEnumerable as IQueryable ? For example, is it supposed to be for cases like this:
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Declaring abstract method in TypeScript
I am trying to figure out how to correctly define abstract methods in TypeScript:
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Using smart pointers for class members
I'm having trouble understanding the usage of smart pointers as class members in C++11. I have read a lot about smart pointers and I think I do understand how unique_ptr and shared_ptr / weak_ptr work in general. What I don't understand is the real usage. It seems like everybody recommends using...
font-style: italic vs oblique in CSS
What is the difference between these two:
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