从csv读取的Javascript d3 [英] Javascript d3 reading from csv

问题描述

好的，所以我是一个javascript的菜鸟，我需要从csv读取数据，用d3制作条形图。条形图对我来说没问题，从csv文件读取是。这是我的代码：

Ok, so I am a bit of a noob with javascript and I need to read data from a csv to make a barchart with d3. The barchart is no problem for me, the reading from the csv file is. This is my code:

var dataset;
    d3.csv("gender_ratio.csv", function(data) {
    dataset = data;
    return dataset;
});

var add = function(year, total, males, females){
    var year = {
        year: year,
        total: total,
        males: males,
        females: females
    };
    newdata.push(year);
    return newdata;
};

for (var i = 0; i < dataset.length; i += 4){
    add(dataset[i], dataset[i+1], dataset[i+2], dataset[i+3]);
    return newdata;
};

有人可以告诉我这里出了什么问题吗？我用modzilla firefox运行它，所以浏览器安全性不是问题。

Can someone tell me what I is going wrong here? I am running this with modzilla firefox, so the browser security isn't the problem here.

推荐答案

首先，d3的 .csv 函数异步，因此您需要在 .csv 函数中调用te实际条形图绘制函数。如果csv文件的第一行包含列名，则可以使用回调函数：

First, d3's .csv function works asynchronous, thus you need to call te actual bar chart drawing function within the .csv function. If the csv file has a first row featuring column names, you can use a callback function:

var dataset = [];
d3.csv("gender_ratio.csv", function(d) {
  return {
    year: d.year,
    total: d.total,
    males: d.males,
    females: d.females,
  };
}, function(error, rows) {
  dataset = rows;
  drawBarChart();  /* <<-- This would be the call to the drawing function. */
});

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