Plotting averages with dc.js / crossfilter
I have some data like this
[
{type:"a", series:[0.1, 0.2, 0.2, 0.1, -0.1]},
{type:"b", series:[0.3, 0.4, 0.5, 0.6, 0.7]},
]
There is a dimension for type, then I'm doing a group and averaging out each series per type.
Is there a nice way to plot the averaged series per type? Obviously I want it to update with any new filters.
I tried flattening out my data as
[
{type:"a", index:0, value:0.1},
{type:"a", index:1, value:0.2},
...
]
and making index a dimension as well. But it's getting a bit slow when I add more data; I never filter the index dimension, so adding it to crossfilter is just an extra cost; and finally it messes up the counts for each type.
尝试这个：
var group = typeDimension.group().reduce(reduceAdd, reduceRemove, reduceInitial);
function reduceAdd(p, v) {
++p.count
p.sum += calculateAverage(v['series']);
p.avg = p.sum / p.count;
return p;
}
function reduceRemove(p, v) {
--p.count
p.sum -= calculateAverage(v['series']);
p.avg = p.sum / p.count;
return p;
}
function reduceInitial() {
return {count: 0, sum: 0, avg: 0};
}
function calculateAverage(numbers) {
var sum = 0;
number.forEach(function(num) {
sum += num;
});
return sum / numbers.length;
}
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