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Count, size, length…too many choices in Ruby?
... an element or predicate and count only those items that match.
> [1,2,3].count{|x| x > 2 }
=> 1
In the case where you don't provide a parameter to count it has basically the same effect as calling length. There can be a performance difference though.
We can see from the source code f...
How do I zip two arrays in JavaScript? [duplicate]
...
Use the map method:
var a = [1, 2, 3]
var b = ['a', 'b', 'c']
var c = a.map(function(e, i) {
return [e, b[i]];
});
console.log(c)
DEMO
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How can I extract all values from a dictionary in Python?
I have a dictionary d = {1:-0.3246, 2:-0.9185, 3:-3985, ...} .
11 Answers
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Python Pandas merge only certain columns
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answered Jul 31 '13 at 18:46
Andy HaydenAndy Hayden
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Fastest way to determine if an integer's square root is an integer
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35 Answers
35
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input() error - NameError: name '…' is not defined
...on 2.7, which will not evaluate the read strings.
If you are using Python 3.x, raw_input has been renamed to input. Quoting the Python 3.0 release notes,
raw_input() was renamed to input(). That is, the new input() function reads a line from sys.stdin and returns it with the trailing newline st...
Is sizeof(bool) defined in the C++ language standard?
...ntation defined, and the standard puts notable emphasis on this fact.
§5.3.3/1, abridged:
sizeof(char), sizeof(signed char) and sizeof(unsigned char) are 1; the result of sizeof applied to any other fundamental type is implementation-defined. [Note: in particular, sizeof(bool) and sizeof(wchar...
Why are preprocessor macros evil and what are the alternatives?
...ly becomes completely the wrong thing....
Replacement: real functions.
3) Macros have no namespace
If we have a macro:
#define begin() x = 0
and we have some code in C++ that uses begin:
std::vector<int> v;
... stuff is loaded into v ...
for (std::vector<int>::iterator it = m...