This seems like it should be trivial. I want to use d3.time.scale() to get an array of evenly spaced dates that covers a certain range of time. For example, years
[2012-01-01, 2013-01-01, 2014-01-01]
or months
[2012-01-01, 2012-02-01, 2012-03-01 ... 2014-12-01]
or whatever.
So I start out like this:
var t = d3.time.scale()
.domain(d3.extent(dates))
.nice(d3.time.year);
I would then assume from the documentation that I'd be able to do this
var ticks = t.ticks(d3.time.month,1);
...but that just returns a single date.
This gives me an array of months
var ticks = t.ticks(30)
...but only because I told it roughly how many ticks to generate (30), which I won't know in advance (unless I do some heavy lifting on my own, which kind of defeats the purpose of using d3 for this).
I don't understand why it's not working to just tell it that I want every year, or every month, or every 3 months, or whatever.
I've put up a fiddle here: /
This seems like it should be trivial. I want to use d3.time.scale() to get an array of evenly spaced dates that covers a certain range of time. For example, years
[2012-01-01, 2013-01-01, 2014-01-01]
or months
[2012-01-01, 2012-02-01, 2012-03-01 ... 2014-12-01]
or whatever.
So I start out like this:
var t = d3.time.scale()
.domain(d3.extent(dates))
.nice(d3.time.year);
I would then assume from the documentation that I'd be able to do this
var ticks = t.ticks(d3.time.month,1);
...but that just returns a single date.
This gives me an array of months
var ticks = t.ticks(30)
...but only because I told it roughly how many ticks to generate (30), which I won't know in advance (unless I do some heavy lifting on my own, which kind of defeats the purpose of using d3 for this).
I don't understand why it's not working to just tell it that I want every year, or every month, or every 3 months, or whatever.
I've put up a fiddle here: http://jsfiddle/herbcaudill/LgGpd/4/
Share Improve this question edited Nov 24, 2013 at 21:37 Herb Caudill asked Nov 24, 2013 at 21:32 Herb CaudillHerb Caudill 50k40 gold badges127 silver badges178 bronze badges 1- Just to clarify, I'm not using this in conjunction with the axis object. I just want an array. – Herb Caudill Commented Nov 24, 2013 at 21:41
2 Answers
Reset to default 5Using the Date() constructor doesn't work reliably -- it basically depends on the browser. It's much safer to parse explicitly. The constructor doesn't parse as such.
Instead of
var dates = getDates().map(function(d) { return new Date(d) });
use this:
var dates = getDates().map(function(d) {
return d3.time.format("%Y-%m-%d").parse(d);
});
Modified jsfiddle here.
Using a dataset such as
var dataset = [
{ "active" : false,
"date" : "2014-12-12"
},
{ "active" : true,
"date" : "2014-12-13"
},
{ "active" : true,
"date" : "2014-12-14"
},
{ "active" : true,
"date" : "2014-12-15"
}
]
var slicedData = var slicedData = dataset.slice();
I had a similar problem, and found that
var x = d3.time.scale()
.domain([new Date(slicedData[0].date), new Date(slicedData[slicedData.length - 1].date)])
.range([0,width]);
Dropped the first item in the scale (it still remains a mystery as to why that was the case), whereas
var dates = slicedData.map(function(d) {
return d3.time.format("%Y-%m-%d").parse(d.date);
});
var t = d3.time.scale()
.domain(d3.extent(dates))
.range([0,width])
.nice(d3.time.day);
worked fine.
So, my only explanation is the one Lars provided. Date() is unpredictable, so use d3.time.format instead.