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Is there a performance gain in using single quotes vs double quotes in ruby?
... x.report("assign double") { n.times do; c = "a string"; end}
x.report("concat single") { n.times do; 'a string ' + 'b string'; end}
x.report("concat double") { n.times do; "a string " + "b string"; end}
end
$ ruby benchmark_quotes.rb
user system total r...
Import multiple csv files into pandas and concatenate into one DataFrame
I would like to read several csv files from a directory into pandas and concatenate them into one big DataFrame. I have not been able to figure it out though. Here is what I have so far:
...
MySQL combine two columns into one column
...t start with a digit, then the converted value is 0.
So try this:
select concat(column1, column2)
Two ways to add a space:
select concat(column1, ' ', column2)
select concat_ws(' ', column1, column2)
share
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...
How do I configure different environments in Angular.js?
...st',
'ngconstant:production',
'useminPrepare',
'concurrent:dist',
'concat',
'copy',
'cdnify',
'ngmin',
'cssmin',
'uglify',
'rev',
'usemin'
]);
So running grunt server will generate a config.js file in app/scripts/ that looks like
"use strict";
angular.module("config", []).co...
How to concatenate two IEnumerable into a new IEnumerable?
...he same T ). I want a new instance of IEnumerable<T> which is the concatenation of both.
4 Answers
...
Iterate two Lists or Arrays with one ForEach statement in C#
...
You can use Union or Concat, the former removes duplicates, the later doesn't
foreach (var item in List1.Union(List1))
{
//TODO: Real code goes here
}
foreach (var item in List1.Concat(List1))
{
//TODO: Real code goes here
}
...
Comparing strings with == which are declared final in Java
... question about strings in Java. The following segment of simple code just concatenates two strings and then compares them with == .
...
How to merge two arrays in JavaScript and de-duplicate items
... just merge the arrays (without removing duplicates)
ES5 version use Array.concat:
var array1 = ["Vijendra", "Singh"];
var array2 = ["Singh", "Shakya"];
console.log(array1.concat(array2));
ES6 version use destructuring
const array1 = ["Vijendra","Singh"];
const array2 = ["Singh", "Shakya"...
Combine multiple Collections into a single logical Collection?
...
With Guava, you can use Iterables.concat(Iterable<T> ...), it creates a live view of all the iterables, concatenated into one (if you change the iterables, the concatenated version also changes). Then wrap the concatenated iterable with Iterables.unmodi...
How many String objects will be created when using a plus sign?
...iteLine(result);
}
then the compiler seems to emit the code using String.Concat as @Joachim answered (+1 to him btw).
If you define them as constants, e.g.:
const String one = "1";
const String two = "2";
const String result = one + two + "34";
or as literals, as in the original question:
Str...