D3.js Traverse Through Nested Array to Find Max Value-CodePudding

I have a nested array that looks like this: Nested Array

I would like to traverse through the nested array and find the max value of the 'value' field situated in grouped_ratings > values > value

I have tried the following and can't seem to figure out the issue.

var yMax = d3.max(grouped_ratings, function(g) {
            return d3.map(g.values, function(v) {
              return d3.max(v.value)
            })
          });

CodePudding user response：

Change d3.map to d3.max and in the inner-most function, you can just return v.value. Here's what it looks like:

d3.max(grouped_ratings, function (g) {
  return d3.max(g.values, function (v) {
    return v.value;
  });
});

Or as a one-liner: d3.max(grouped_ratings, g => d3.max(g.values, v => v.value))

These snippets work when grouped_ratings has the format

grouped_ratings = [
  {
    key: '2011',
    values: [
      { key: '1', value: 151 },
      { key: '2', value: 12 },
      { key: '3', value: 314 },
      { key: '4', value: 178 },
      { key: '5', value: 31 },
      { key: '6', value: 1 },
      { key: '7', value: 1 },
    ]
  },
  {
    key: '2012',
    values: [
      { key: '1', value: 203 },
      { key: '2', value: 4 },
      { key: '3', value: 41 },
      { key: '4', value: 87 },
      { key: '5', value: 13 },
      { key: '6', value: 10 },
      { key: '7', value: 100 },
    ]
  },
]