使用地图创建字典&过滤？ [英] Creating dictionary with map & filter?

问题描述

我有以下地图和过滤功能，以便将我们的csv文件数据及其列名作为键。

I have the following map and filter functions in order to get my csv file data with their column names as keys.

d3.csv("Sales Export Friendly 3-19-17.csv", function(data) {
    sales = data
        .map(sale => [
        sale["Unit Booked"],
        new Date(sale["Booking Date"]).getMonth() + 1,
        new Date(sale["Checkin"]).getMonth() + 1,
        (new Date(sale["Checkout"]).valueOf() - new Date(sale["Checkin"]).valueOf())/(24*60*60*1000),
        +sale["Total Stay"],
        (+sale["Total Stay"]) / ((new Date(sale["Checkout"]).valueOf() - new Date(sale["Checkin"]).valueOf())/(24*60*60*1000)),
        ])
        .filter(([unit, date, checkin, LOS, total, avgNight]) => !isNaN(total));

这适用于大多数用途，但我还没有想出如何保留列名称以在d3多维类型的viz（并行坐标）中将它们引用为轴。我认为它可能与使用有关地图和过滤器？

This works for most purposes but I haven't figured out how to retain the column names to reference them as axes in a d3 multidimensional type of viz (parallel coordinates). I think it may have to do with the use of map and filter?

推荐答案

什么时候你广告CSV文件， d3.csv 创建一个名为 columns 的便捷数组属性。

When you load a CSV file, d3.csv creates a handy array property called columns.

根据 API ：

返回的数组还公开了一个包含列名的列属性输入顺序（与Object.keys相反，其迭代顺序是任意的）。

The returned array also exposes a columns property containing the column names in input order (in contrast to Object.keys, whose iteration order is arbitrary).

因此，因为你的回调参数名为 data ，您只需使用以下命令获取列的名称：

Thus, since your callback parameter is named data, you can get the columns' names simply using:

data.columns

或者将其分配给变量：

var myColumns = data.columns

这是一个演示版来自此 Bostock的bl.ocks 的真实CSV文件：

Here is a demo with a real CSV file from this Bostock's bl.ocks:

d3.csv("https://gist.githubusercontent.com/mbostock/3887051/raw/805adad40306cedf1a513c252ddd95e7c981885a/data.csv", function(data){
  console.log(data.columns);
});

<script src="https://d3js.org/d3.v4.min.js"></script>

PS：这个答案是指D3 v4，它应该是答案的默认版本，除非在问题中另有说明。

PS: this answer refers to D3 v4, which should be the default version for answers, unless stated otherwise in the question.

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