javascript 如何从数据中选择 d3.js 中的唯一值
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How to select unique values in d3.js from data
提问by ahmohamed
I am using the following code to populate my Combobox using d3.js
我正在使用以下代码使用 d3.js 填充我的 Combobox
d3.csv("Results_New.txt", function(data) {
dataset=data;
d3.select("#road").selectAll("option")
.data(data).enter().append("option").text(function(d){return d.roadname;}).attr("value",function(d){return d.roadname;});
});
There are different rows with the same name. The combobox is populating with these duplicate names. For example in multiple rows the name of the road is I-80.But in the combobox I want to see I-80 only once. How can I do that?
存在具有相同名称的不同行。组合框正在填充这些重复的名称。例如，在多行中，道路名称是 I-80。但在组合框中，我只想看到 I-80 一次。我怎样才能做到这一点？
回答by ahmohamed
Filter your data retaining unique keys only by d3.map
仅通过以下方式过滤保留唯一键的数据 d3.map
d3.select("#road").selectAll("option")
.data(d3.map(data, function(d){return d.roadname;}).keys())
.enter()
.append("option")
.text(function(d){return d;})
.attr("value",function(d){return d;});
回答by Nevershowmyface
Try this:
试试这个：
/* file.csv
name_of_my_header
mom
dad
brother
sister
dog
*/
button.onclick = function() {
var s = d3.select("#road");
d3.csv(prompt("URL please"), function(dataset){
dataset.forEach(function(row) {
s.append("option").text(row["name_of_my_header"]);
})
})
}<select id="road">
</select>
<button id="button">Is it?</button>