[英]calculate the occurence and store the result in a key value-pair using javascript
我需要计算名称在数组中的出现。
var eachAuthorData = ["bob","joke","hello","stack","stack","ok","joke","bob"];
我可以通过使用for循环来做到这一点,并得到这样的结果
{bob: 2, joke: 2, hello: 1, stack: 2, ok: 1}
但结果只能是使用
counts["bob"]
我不仅需要知道每个名字的出现。 但还需要知道数组eachAuthorData中有多少个不同的名称我如何在eachAuthorData中找到bob我只需要使用一次名称
如果以数组开头:
var eachAuthorData = ["bob","joke","hello","stack","stack","ok","joke","bob"];
并且您想知道数组中每个名称有多少个,以及有多少个唯一的字符串,可以这样做:
var counts = {}, i, item, uniques = 0;
for (i = 0; i < eachAuthorData.length; i++) {
item = eachAuthorData[i];
if (!counts.hasOwnProperty(item)) {
counts[item] = 1;
++uniques;
} else {
++counts[item];
}
}
这将产生如下counts
的输出:
{bob: 2, joke: 2, hello: 1, stack: 2, ok: 1}
并且,由于您在注释中提出了其他一些问题,因此我添加了变量uniques
,该变量为您提供了总的唯一字符串数。
并且,您将访问任何单个计数,如下所示:
var cnt = counts["bob"];
或者,如果所需的键在名为key
的变量中,则可以使用:
var cnt = counts[key];
如果要迭代所有唯一字符串的所有计数,则可以这样进行:
for (var item in counts) {
// item is the key
// counts[item] is the count
console.log("counts[" + item + "] = " + counts[item]);
}
工作演示: http : //jsfiddle.net/jfriend00/eJyAg/
如果要获取counts对象中键的列表(例如,唯一字符串),可以使用:
var keys = Object.keys(counts);
Object.keys()
需要IE9或更高版本,或者如果您想与IE的较早版本进行互操作,请在此处使用polyfill。
我认为您应该具有:
var eachAuthorData = ["bob","joke","hello","stack","stack","ok","joke","bob"];
这样做计算:
var toMatch, i, count;
toMatch = "bob";
count = 0;
for( i=0 ; i<eachAuthorData.length ; ++i ){
if( eachAuthorData[i] == toMatch ){
++count;
}
}
console.log("The element "+ toMatch +" is counted "+ count +" times!");
试试这个
var tempObject = new Object();
function count() {
array_elements = ["bob","joke","hello","stack","stack","ok","joke","bob"];
array_elements.sort();
var current = null;
var cnt = 0;
for (var i = 0; i < array_elements.length; i++) {
if (array_elements[i] != current) {
if (cnt > 0) {
tempObject[current]=cnt;
console.log(current + ' comes --> ' + cnt + ' times<br>');
}
current = array_elements[i];
cnt = 1;
} else {
cnt++;
}
}
if (cnt > 0) {
console.log(current + ' comes --> ' + cnt + ' times');
tempObject[current]=cnt;
}
}
count();
console.log(JSON.stringify(tempObject));
大概你的意思是这样的数组:
var data = ["bob","joke","hello","stack","stack","ok","joke","bob"];
由于其他人走了明显的路,我将发布一些更健壮的方法,以说明数据数组已删除成员的可能性(即稀疏):
function countMembers(dataArray) {
for (var i=0, iLen=dataArray.length, o={}, item; i<iLen; i++) {
item = dataArray[i];
if (dataArray.hasOwnProperty(i)) {
if (o.hasOwnProperty(item)) {
++o[item];
} else {
o[item] = 1;
}
}
}
return o;
}
鉴于:
["bob","joke",,,,"hello","stack","stack","ok","joke","bob"];
其他将包括一个undefined: 3
成员undefined: 3
,但是上面没有。
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