what is the d3 default key function?
Question
Trying to figure out what the default key function is in d3.
If the three <p> elements I include in my html body have keys of 0,1,2, and I am using the d3 enter() function to append <p> elements with keys of 0,1,5 why does my d3 code add all <p> elements to my page and not just the <p> with key of 5?
<html>
<head>
<script src="http://d3js.org/d3.v3.min.js" charset="utf-8"></script>
</head>
<body>
<p>joe</p>
<p>joe</p>
<p>joe</p>
<script type="text/javascript">
d3.select("body").selectAll("p")
.data([ 0, 1, 5], function(d){ return d; })
.enter()
.append("p")
.text(function(d){ return d; });
</script>
</body>
</html>
jsfiddle: http://jsfiddle.net/266z3dr1/
1 answers
solution1
3 ACCPTED 2014-09-24 16:42:28
If a
keyfunction is not specified, then the first datum in the specified array is assigned to the first element in the current selection, the second datum to the second selected element, and so on.
You are getting three new elements because none of the existing ones has a key. Data association is either index-based (default) or key-based (if a key function is passed).
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