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How to randomly pick an element from an array
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You can use the Random generator to generate a random index and return the element at that index:
//initialization
Random generator = new Random();
int randomIndex = generator.nextInt(myArray.length);
return myArray[randomIndex];
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MySQL with Node.js
...de.js. I come from a PHP background, so I'm fairly used to using MySQL for all my database needs.
9 Answers
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How can I count the number of matches for a regex?
... i.e. this behavior:
aaaa
aa
aa
aa
You have to search for a match at index <start of last match> + 1 as follows:
String hello = "aaaa";
Pattern pattern = Pattern.compile("aa");
Matcher matcher = pattern.matcher(hello);
int count = 0;
int i = 0;
while (matcher.find(i)) {
count++;
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How do I sort one vector based on values of another
...but I will leave this in for posterity.]
You can do this without loops by indexing on your y vector. Add an incrementing numeric value to y and merge them:
y <- data.frame(index=1:length(y), x=y)
x <- data.frame(x=x)
x <- merge(x,y)
x <- x[order(x$index),"x"]
x
[1] 4 4 4 2 2 1 3 3 3
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What happens to C# Dictionary lookup if the key does not exist?
...'t in dictionary; "value" is now 0
}
(Using ContainsKey and then the the indexer makes it look the key up twice, which is pretty pointless.)
Note that even if you were using reference types, checking for null wouldn't work - the indexer for Dictionary<,> will throw an exception if you reque...
jquery.validate.unobtrusive not working with dynamic injected elements
...ate it to include the code in the comments otherwise it can break. Specifically, change the two selector lines to double quote the id.
– Ryan O'Neill
Jul 14 '11 at 19:50
1
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How can I make an entire HTML form “readonly”?
...elements inside the form element, since that layer is set with a greater z-index value:
DEMO:
var form = document.forms[0], // form element to be "readonly"
btn1 = document.querySelectorAll('button')[0],
btn2 = document.querySelectorAll('button')[1]
btn1.addEventListener('click', ...
Get month name from number
... you can see that calendar.month_name[3] would return March, and the array index of 0 is the empty string, so there's no need to worry about zero-indexing either.
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How do I detect the Python version at runtime? [duplicate]
... @NauticalMile Chris's answer also returns a string, he's just indexing into the first character to see if it is '3' or not; the same would work here.
– weberc2
Oct 9 '17 at 13:57
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How to keep keys/values in same order as declared?
...simple array with integers for the sparse hash table, where those integers index into another array that stores the key-value pairs (plus the calculated hash). That latter array just happens to store the items in insertion order, and the whole combination actually uses less memory than the implement...