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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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how to append a list object to another
in C++, I have two list<T> objects A and B and I want to add all the members of B to the end of A . I've searched a few different sources and haven't found a simple solution (e.i. A.append(B); ) and this surprises me a bit.
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How to replace all occurrences of a string?
...n(replacement)
This used to be faster in some cases than using replaceAll and a regular expression, but that doesn't seem to be the case anymore in modern browsers.
Benchmark: https://jsperf.com/replace-all-vs-split-join
Conclusion: If you have a performance critical use case (e.g processing hundre...
Role/Purpose of ContextLoaderListener in Spring?
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Your understanding is correct. The ApplicationContext is where your Spring beans live. The purpose of the ContextLoaderListener is two-fold:
to tie the lifecycle of the ApplicationContext to the lifecycle of the ServletContext and
to...
Managing constructors with many parameters in Java
...e("Spicoli")
.age(16)
.motto("Aloha, Mr Hand")
.buildStudent();
If we leave off a required field (presumably name is required) then we can have the Student constructor throw an exception.
And it lets us have default/optional arguments without need...
Mean per group in a data.frame [duplicate]
I have a data.frame and I need to calculate the mean per group (i.e. per Month , below).
8 Answers
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