如何在DC /交叉滤波器维度中过滤多个值？ [英] How to filter multiple values in a dc/crossfilter dimension?

问题描述

让我说我有以下数据和维度：

Let me say that I have this data and dimension:

var data = [
      {"fruit": "apple", "amount": "12"},
      {"fruit": "orange", "amount": "6"},
      {"fruit": "grape", "amount": "11"},
      {"fruit": "melon", "amount": "26"},
      {"fruit": "lemon", "amount": "15"}
    ]

var ndx = crossfilter(data);
var fruitDimension = ndx.dimension(function (d) {
                            return d.fruit;
                        });

...现在，我只想过滤苹果，柠檬和橙色 ，只需使用代码即可。现在，我正在尝试做类似的事情。

...and now, I want to filter just "apple","lemon" and "orange" just by using code. By now, I am trying to do something like.

fruitDimension.filter(["apple","lemon","orange"])

...但是它不能全部正常工作。

...but it does not work it all.

• 我知道函数＃ dimension.filterExact（value）适用于一个值。

• 如果我应用＃ dimension.filter（value），则将向量作为参数进行处理与它作为＃Dimension.filterRange（范围）

• If I apply # dimension.filter(value) passing a vector as parameter, it deals with it as # dimension.filterRange(range)

我找不到哪个过滤器适用于不同的值。

I could not find which filter works for different values.

引用来自： https://github.com/square/crossfilter/wiki/API-Reference

有人暗示我可以做什么，以便过滤维度的不同元素（不遵循范围顺序）？

Someone has a hint about what I could be doing in order to filter different elements (that do not follow a range order) of a dimension?

在此先感谢
Roger

Thanks in advance, Roger

推荐答案

交叉过滤器为此需要一个自定义过滤器功能。 dc.js提供了一个。

Crossfilter requires a custom filter function for this. dc.js supplies one.

如果您使用的是dc图表，您应该通过图表的 filter 函数应用该过滤器，该函数的语法和语义与交叉过滤器维度过滤器不同：

If you're using a dc chart you should apply the filter via the chart's filter function, which has different syntax and semantics from the crossfilter dimension filter:

chart.filter([["apple","lemon","orange"]]);

请注意多套括号。对吗？我不知道它是如何演变的。此外，dc会切换每个值，因此，如果要替换过滤器，请使用 replaceFilter 代替 filter 。

Note the extra set of brackets. Weird right? I do not know how it evolved this way. Also, dc will toggle each value, so if you want to replace the filter, use replaceFilter instead of filter.

这在 filterHandler 函数，这是dc.js将过滤器应用于交叉过滤器的地方。

This is documented in the filterHandler function, which is where dc.js applies filters to crossfilter.

图表不直接知道交叉过滤器维度的变化：如果使用图表的 .filter（）>然后图表将更新视觉选择。

The chart doesn't know about changes directly to the crossfilter dimension: if you use the chart's .filter() then the chart will update the visual selection.

如果您想应用将多值过滤器直接转换为交叉过滤器维度，这是一个为值数组生成过滤器函数的函数：

If instead you want to apply a multivalue filter directly to a crossfilter dimension, here is a function that generates a filter function for an array of values:

function multivalue_filter(values) {
    return function(v) {
        return values.indexOf(v) !== -1;
    };
}
fruitDimension.filterFunction(multivalue_filter(["apple","lemon","orange"]));

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