Find the maximum value in an object where the keys are arrays? - d3.js

Question

Using D3, how can I find the maximum value in an object where all the values are arrays of floats?
var data = {
"point1": {
"level1": [...],
"level2": [...]
},
...
};
I read Mike's answer on finding the max of a nested array, but I'm not sure what to do here since this is an object of arrays.
Currently I'm doing this, which is awful:
var c1Max = d3.max(data.point1.level1, function(d) { return d.value; });
var c2Max = d3.max(data.point1.level2, function(d) { return d.value; });
var c3Max = d3.max(data.point2.level1, function(d) { return d.value; });
var c4Max = d3.max(data.point2.level2, function(d) { return d.value; });
var c5Max = d3.max(data.point3.level1, function(d) { return d.value; });
var c6Max = d3.max(data.point3.level2, function(d) { return d.value; });
var max = d3.max([c1Max, c2Max, c3Max, c4Max, c5Max, c6Max]);
Maybe I should iterate over all the keys? Or maybe I could flatten the data object somehow? Or maybe there's a nicer way.

Answer 1

You can use d3.entries to convert the object into something you can iterate over:
var max = d3.max(d3.entries(data), function(d) {
return d3.max(d3.entries(d.value), function(e) {
return d3.max(e.value);
});
});
In this particular case (keys not required) you can of course also use d3.values, which makes the above code a bit shorter.
To make it work with the structure in your jsfiddle, you need this code:
var max1 = d3.max(d3.entries(data), function(d) {
return d3.max(d3.entries(d.value), function(e) {
return d3.max(e.value, function(f) { return f.value; });
});
});