Извлечение определенного индекса массива в d3 select

Question

Следующее выбирает все элементы из соединений массива. Я просто хочу особого.

var route = vis.selectAll("line.route") 
.data(connections) 
.enter().append("svg:line") 
    .attr("class", "route") 
    .attr("stroke", function(d) { return '#'+routesById[d.line].colour; }) 
    .attr("stroke-linecap", 'round') 
    .attr("x1", function(d) { return x(d.station1.longitude); }) 
    .attr("y1", function(d) { return y(d.station1.latitude); }) 
    .attr("x2", function(d) { return x(d.station2.longitude); }) 
    .attr("y2", function(d) { return y(d.station2.latitude); }) 

соединение является массив (я думаю), и на консоли определяется как

[Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object…] 

Однако я только хочу, чтобы выбрать элемент в определенном индексе. Я попытался использовать фильтр, но он не сработал?

.data(connections.filter(function(d) { return d[23] })) 

Answer 1

использование я

.data(connections.filter(function(d,i) { return i === 23; })) 

https://github.com/mbostock/d3/wiki/Selections#filter