Javascript 使用下划线 groupby 按颜色对一组汽车进行分组
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Using underscore groupby to group an array of cars by their colour
提问by Jon Wells
I have an array of cars.
我有很多车。
car = {
make: "nissan",
model: "sunny",
colour: "red"
};
How would I use underscore.js to group the array by colour?
我将如何使用 underscore.js 按颜色对数组进行分组？
I've tried a few combos but I'm not really sure how to specify my iterator condition:
我尝试了一些组合，但我不确定如何指定我的迭代器条件：
var carsGroupedByColor = _.groupBy(cars, false, colour);
var carsGroupedByColor = _.groupBy(vars, false, function(cars){ return cars[colour]; };
They all return everything in the array each time.
它们每次都返回数组中的所有内容。
回答by jabclab
You don't need the falsesecond argument, the following will work:
您不需要false第二个参数，以下将起作用：
var redCars = _.groupBy(cars, 'colour');
Note that the second parameter can either be a functionor a string. If it's a stringUnderscore groups by that property name.
请注意，第二个参数可以是 afunction或 a string。如果它是string该属性名称的下划线组。
Taken from the docs:
取自文档：
Splits a collection into sets, grouped by the result of running each value through iterator. If iteratoris a string instead of a function, groups by the property named by iteratoron each of the values.
将集合拆分为多个集合，按通过迭代器运行每个值的结果分组。如果迭代器是字符串而不是函数，则按迭代器命名的属性对每个值进行分组。
Here's a working example.
这是一个工作示例。
回答by Jon Taylor
I've never used underscore js but would it not be as per their docs
我从来没有使用过下划线 js 但它不会按照他们的文档
var groupedCars = _.groupBy(cars, function(car) { return car.make; });
In fact I believe this ir more correct since it states that if the iterator is a string instead it groups by the property in the object with that string name.
事实上，我认为这更正确，因为它指出如果迭代器是一个字符串，它会根据对象中具有该字符串名称的属性进行分组。
var groupedCars = _.groupBy(cars, "make");
If you then want just the red cars (even though you really should be using a filter I guess) then you can do the following
如果您只想要红色汽车（即使您确实应该使用过滤器，我猜）那么您可以执行以下操作
var redCars = groupedCars["red"];
To use a filter instead
改用过滤器
Looks through each value in the list, returning an array of all the values that pass a truth test (iterator). Delegates to the native filter method, if it exists.
查看列表中的每个值，返回所有通过真值测试（迭代器）的值的数组。委托给本机过滤器方法（如果存在）。
var redCars = _.filter(cars, function(car) { return car.colour == "red" });
回答by Dheeraj Nalawade
var data = [
{
"name": "jim",
"color": "blue",
"age": "22"
},
{
"name": "Sam",
"color": "blue",
"age": "33"
},
{
"name": "eddie",
"color": "green",
"age": "77"
},
{
"name": "Dheeraj",
"color": "blue",
"age": "25"
},
{
"name": "Suraj",
"color": "green",
"age": "25"
}
];
var result = _.groupBy(data,"color");
console.log(result);
