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How to drop columns by name in a data frame
I have a large data set and I would like to read specific columns or drop all the others.
11 Answers
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C++ map access discards qualifiers (const)
... as const, and cannot be due to its behavior:
T& operator[] (const Key& key)
Returns a reference to the value that is mapped to a key equivalent to key, performing insertion if such key does not already exist.
As a result, your function cannot be declared const, and use the map's...
Difference between '..' (double-dot) and '…' (triple-dot) in range generation?
...inclusively. Those created using ... exclude the end value.
So a..b is like a <= x <= b, whereas a...b is like a <= x < b.
Note that, while to_a on a Range of integers gives a collection of integers, a Range is not a set of values, but simply a pair of start/end values:
(1..5).incl...
How do you 'redo' changes after 'undo' with Emacs?
...ndo will undo the undo, resulting in a redo.
Longer version:
You can think of undo as operating on a stack of operations. If you perform some command (even a navigation command such as C-f) after a sequence of undo operations, all the undos are pushed on to the operation stack. So the next undo u...
How to create SBT project with IntelliJ Idea?
I just got started with Scala/LiftWeb/Sbt developing, and I'd like to import a Sbt project in IntelliJ Idea.
Actually, I managed to import my project in two different ways:
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iPhone/iOS JSON parsing tutorial [closed]
As a learning experience, I want to make an iPhone application that calls a webserver/webservice, retrieves a JSON response, and uses that response to populate the rows of a UITableView (assuming it converts the JSON into an NSArray first).
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Check whether an array is empty [duplicate]
...ts in array and this definitely doesn't mean that array is empty. As a quick workaround you can do following:
$errors = array_filter($errors);
if (!empty($errors)) {
}
array_filter() function's default behavior will remove all values from array which are equal to null, 0, '' or false.
Otherwise...
Get div height with plain JavaScript
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DanDan
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Which is preferred: Nullable.HasValue or Nullable != null?
I always used Nullable<>.HasValue because I liked the semantics. However, recently I was working on someone else's existing codebase where they used Nullable<> != null exclusively instead.
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Stylecop vs FXcop
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Stylecop is a style analysis tool that works at the source code level. It exists primarily to provide a single common style that managed projects can use to remain consistent within the larger world of managed software. It makes decisions regarding style primarily ...