I have:
myArray = ["ABAB", "ABAB", "ABAB", "CDCD", "EFEF", "EFEF"]
I need to count by occurrences and sort by highest count. This would be the return:
ABAB 3
EFEF 2
CDCD 1
Note, the parameters inside the array are constantly changed so by "grepping" for each static or literal text pattern won't help.
Any idea of the fastest way to accomplish this either with JQuery or plain JS?
Step one: build the histogram, as a map element -> its frequency for speed (assumes all elements are strings):
var histogramMap = {};
for(var i=0, len=myArray.length; i<len; i++){
var key = myArray[i];
histogramMap[key] = (histogramMap[key] || 0) + 1;
}
Step two: convert to an array of output objects:
var histogram = [];
for(key in histogramMap) histogram.push({key: key, freq: histogramMap[key]});
Step three: sort the histogram
histogram.sort(function(a,b){return b.freq - a.freq})
This also assumes that Object.prototype is not modified. This is a safe assumption to make, and lots (I think) of libraries, including jQuery, make that assumption. But, if you decide to add enumerable properties to Object.prototype, these will be picked up by for..in. If you want to be safe, modify the second step to:
var histogram = [];
for(key in histogramMap){
if(histogramMap.hasOwnProperty(i)){
histogram.push({key: key, freq: histogramMap[key]});
}
}
Object.prototype has no enumerable properties. In the situations where hasOwnProperty is needed in my code, jQuery breaks ;-) I habitually leave out hasOwnProperty when looping over plain objects.I recently created a library with such a function.
var items = {}, sortableItems = [], i, len, element,
listOfStrings = ["ABAB", "ABAB", "ABAB", "CDCD", "EFEF", "EFEF"];
for (i = 0, len = listOfStrings.length; i < len; i += 1) {
if (items.hasOwnProperty(listOfStrings[i])) {
items[listOfStrings[i]] += 1;
} else {
items[listOfStrings[i]] = 1;
}
}
for (element in items) {
if (items.hasOwnProperty(element)) {
sortableItems.push([element, items[element]]);
}
}
sortableItems.sort(function (first, second) {
return second[1] - first[1];
});
console.log(sortableItems);
Output
[ [ 'ABAB', 3 ], [ 'EFEF', 2 ], [ 'CDCD', 1 ] ]
Try this:
array_elements = ["ABAB", "ABAB", "ABAB", "CDCD", "EFEF", "EFEF"];
var result_array = [];
var current = null;
var cnt = 0;
for (var i = 0; i < array_elements.length; i++) {
if (array_elements[i] != current) {
if (cnt > 0) {
result_array.push([current,cnt]);
}
current = array_elements[i];
cnt = 1;
} else {
cnt++;
}
}
if (cnt > 0) {
result_array.push([current,cnt]);
}
result_array.sort(function(x,y) {return y[1] - x[1]})
alert(result_array);
The result_array will have the result.
document.write. One, it's evil. Two, you don't know if your code is running at the moment when DW is just slow. Third, you are not supposed to print anything.
see console in firefox to see the resulting object
myArray = ["ABAB", "ABAB", "ABAB", "CDCD", "EFEF", "EFEF"];
container={};
for(var i=0; i < myArray.length;i++){
var el=myArray[i];
if( el in container){
container[el].push(el);
}
else{
container[el]=[];
container[el].push(el);
}
}
console.log(container);
for..in for arrays. You could pick up shimmed methods and other non-numeric properties. Also, the iteration order is not specified (not really an issue here).["abab", "abab", "abab"] is an efficient way to represent that "abab" occurs three times. Also, you don't sort the results by frequency.
$array = array("ABAB", "ABAB", "ABAB", "CDCD", "EFEF", "EFEF");
$array1=array_count_values($array);
arsort($array1);
foreach($array1 as $x=>$x_value)
{
echo "Key=" . $x . ", Value=" . $x_value;
echo "<br>";
}
<br>s. Even for testing, <p>s work better.