如何用d3 v4读取CSV？ [英] How to read in CSV with d3 v4?
问题描述
我只是在理解带有D3的CSV解析。我目前有：
d3.parse（data.csv，function（data）{
salesData = data ;
}）;
但我一直收到错误：
< blockquote>
未捕获TypeError：d3.parse不是函数
这应该是什么样子？我只是有点困惑，我能找到的唯一例子就是这个。
我也尝试过这样的事情：
d3.dsv.parse （data.csv，函数（数据）{
salesData = data;
}）;
并得到：
Uncaught TypeError：无法读取未定义的属性'parse'
为什么会发生这种情况？任何帮助都会有很大的帮助，谢谢!!
这里有一些误解：你很困惑 d3.csv ，这是一个请求，带有 d3.csvParse ，它解析一个字符串（并将D3 v3函数与D3 v4函数混合）。这是区别：
d3.csv（D3 v4）
d3.csv 函数，它以为参数（url [ [，row]，callback]）：
返回CSV 文件<的新请求/ strong>在指定的 url 上使用默认的mime类型text / csv。 （强调我的）
所以，正如你所看到的，你使用 d3.csv 当您想要在给定网址上请求给定的CSV文件时。
例如，下面的代码段会在引号之间的网址上获取CSV，如下所示...
姓名，父母
等级2：A，顶级
顶级，null
A之子，等级2：A
A女儿，等级2：A
等级2：B，顶级
...并记录解析后的CSV文件，检查它：
d3.csv（https://gist.githubusercontent.com/d3noob/fa0f16e271cb191ae85f/raw/bf896176236341f56a55b36c8fc40e32c73051ad/treedata.csv，function（data）{console.log（data） ;}）;
< script src =https： / /d3js.org/d3.v4.min.js\"></script>
d3.csvParse
另一方面， d3.csvParse （或D3 v3中的 d3.csv.parse ）， arguments （string [，row]）：
解析指定的字符串，必须使用适当的分隔符以分隔符分隔的值格式，返回表示已解析行的对象数组。
所以，你当你想解析一个字符串时，使用 d3.csvParse 。
这是一个演示，假设你有这个字符串：
var data =foo，bar，baz \ nn42,33,42 \ nn12,76,54 \ n13,42,17\" ;
如果要解析它，你将使用 d3.csvParse ，而不是 d3.csv ：
var data =foo，bar，baz \ nn42,33,42 \ n12,76,54 \ nn13,42,17; var parsed = d3.csvParse（data ）; console.log（已解析）;
< script SRC = https://d3js.org/d3.v4.min.js >< /脚本>
I'm just having a little trouble understanding the documentation for CSV Parse with D3. I currently have:
d3.parse("data.csv",function(data){
salesData = data;
});
But I keep on getting the error:
Uncaught TypeError: d3.parse is not a function
What is this supposed to look like? I'm just a little confused, and the only examples that I could find was something like this.
I also tried something like:
d3.dsv.parse("data.csv",function(data){
salesData = data;
});
and got:
Uncaught TypeError: Cannot read property 'parse' of undefined
Why is this happening? Any help would be greatly appreaciated, thanks!!
There is some misunderstanding here: you're confusing d3.csv, which is a request, with d3.csvParse, which parses a string (and also mixing D3 v3 functions with D3 v4 functions). This is the difference:
d3.csv (D3 v4)
The d3.csv function, which takes as arguments (url[[, row], callback]):
Returns a new request for the CSV file at the specified url with the default mime type text/csv. (emphasis mine)
So, as you can see, you use d3.csv when you want to request a given CSV file at a given url.
For example, the snippet below gets the CSV at the url between quotes, which looks like this...
name, parent
Level 2: A, Top Level
Top Level, null
Son of A, Level 2: A
Daughter of A, Level 2: A
Level 2: B, Top Level
... and logs the parsed CSV file, check it:
d3.csv("https://gist.githubusercontent.com/d3noob/fa0f16e271cb191ae85f/raw/bf896176236341f56a55b36c8fc40e32c73051ad/treedata.csv", function(data){
console.log(data);
});
<script src="https://d3js.org/d3.v4.min.js"></script>
d3.csvParse
On the other hand, d3.csvParse (or d3.csv.parse in D3 v3), which takes as arguments (string[, row]):
Parses the specified string, which must be in the delimiter-separated values format with the appropriate delimiter, returning an array of objects representing the parsed rows.
So, you use d3.csvParse when you want to parse a string.
Here is a demo, suppose you have this string:
var data = "foo,bar,baz\n42,33,42\n12,76,54\n13,42,17";
If you want to parse it, you'll use d3.csvParse, not d3.csv:
var data = "foo,bar,baz\n42,33,42\n12,76,54\n13,42,17";
var parsed = d3.csvParse(data);
console.log(parsed);
<script src="https://d3js.org/d3.v4.min.js"></script>
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