Question

我想计算从.csv文件导入的15分钟数据的最大值。文件中的每一行都包含来自不同日期（"ID"）的不同来源（"Date"）的15分钟数据，但是不需要其他列（"Class", "Sample", "Channel"）供我分析。

我看过使用d3.group，但是似乎没有五个键值（每个非数字值一个）是正确的解决方法。

导入数据如下：

[
  {
    "ID": "10D1012B",
    "Class": "R",
    "Sample": "135_OLD",
    "Channel": "1",
    "Date": "1/1/2019",
    "00:15": "0.48",
    "00:30": "0.6",
    "00:45": "0.896",
    "01:00": "0.712",
    "01:15": "1.12",
          ...
    "23:00": "0.48",
    "23:15": "0.6",
    "23:30": "0.624",
    "23:45": "0.552",
    "00:00": "0.704"
  },
  {
    "ID": "10D1040B",
    "Class": "R",
    "Sample": "135_OLD",
    "Channel": "1",
    "Date": "1/2/2019",
    "00:15": "1.016",
         ...
    "23:30": "0.632",
    "23:45": "0.72",
    "00:00": "0.776"
  }
]

我想计算每一行数据（ID，日期对）的最大值，因此可以使用它来创建图表比例。我不清楚在计算最大值时如何排除非数字列。

Answer 1

您有两个问题：首先，d3.max在相同的数组中遍历不同的对象 ...但是，您需要遍历不同的值在同一 object 中。其次，您也不想包含一些数值，例如"Channel"属性。因此，这并不像在属性中找到所有数值那样简单。

话虽如此，这是我的建议：设置您不想检查的属性名称或键的列表...

const nonNeededKeys = ["ID", "Class", "Sample", "Channel", "Date"];

...，然后对阵列内每个对象中的所有其他键使用d3.max：

data.forEach(function(row) {
  const keys = d3.keys(row).filter(function(d) {
    return nonNeededKeys.indexOf(d) === -1;
  });
  row.maxValue = d3.max(keys.map(function(d) {
    return +row[d]
  }))
});

如您所见，在这里，对于每个对象，我正在创建一个名为maxValue的新属性。

这是演示：

const data = [{
    "ID": "10D1012B",
    "Class": "R",
    "Sample": "135_OLD",
    "Channel": "1",
    "Date": "1/1/2019",
    "00:15": "0.48",
    "00:30": "0.6",
    "00:45": "0.896",
    "01:00": "0.712",
    "01:15": "1.12",
    "23:00": "0.48",
    "23:15": "0.6",
    "23:30": "0.624",
    "23:45": "0.552",
    "00:00": "0.704"
  },
  {
    "ID": "10D1040B",
    "Class": "R",
    "Sample": "135_OLD",
    "Channel": "1",
    "Date": "1/2/2019",
    "00:15": "1.016",
    "23:30": "0.632",
    "23:45": "0.72",
    "00:00": "0.776"
  }
];

const nonNeededKeys = ["ID", "Class", "Sample", "Channel", "Date"];

data.forEach(function(row) {
  const keys = d3.keys(row).filter(function(d) {
    return nonNeededKeys.indexOf(d) === -1;
  });
  row.maxValue = d3.max(keys.map(function(d) {
    return +row[d]
  }))
});

console.log(data)

<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/5.7.0/d3.min.js"></script>

此后，很容易计算所有对象的最大值：

const maxValue = d3.max(data, function(d) {
    return d.maxValue;
});

正在运行的代码段：

const data = [{
    "ID": "10D1012B",
    "Class": "R",
    "Sample": "135_OLD",
    "Channel": "1",
    "Date": "1/1/2019",
    "00:15": "0.48",
    "00:30": "0.6",
    "00:45": "0.896",
    "01:00": "0.712",
    "01:15": "1.12",
    "23:00": "0.48",
    "23:15": "0.6",
    "23:30": "0.624",
    "23:45": "0.552",
    "00:00": "0.704"
  },
  {
    "ID": "10D1040B",
    "Class": "R",
    "Sample": "135_OLD",
    "Channel": "1",
    "Date": "1/2/2019",
    "00:15": "1.016",
    "23:30": "0.632",
    "23:45": "0.72",
    "00:00": "0.776"
  }
];

const nonNeededKeys = ["ID", "Class", "Sample", "Channel", "Date"];

data.forEach(function(row) {
  const keys = d3.keys(row).filter(function(d) {
    return nonNeededKeys.indexOf(d) === -1;
  });
  row.maxValue = d3.max(keys.map(function(d) {
    return +row[d]
  }))
});

const maxValue = d3.max(data, function(d) {
  return d.maxValue
})
console.log(maxValue)

<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/5.7.0/d3.min.js"></script>

使用一些非数字值从数组计算最大值

1 个答案: