Using JavaScript's `Map` function instead of a traditional `for`

My dataset consists of a csv file containing 5000 rows, with each row having thirty fields representing measurements of different chemical elements.

I aim to parse and visualize this data using D3js. Upon reading the file, I obtain an array of length 5000 where each element is an object holding measurements of various chemical elements. For example, measurements[5].Aluminium provides the concentration of Aluminium at the fifth measurement.

Instead of individual values, I wish to organize the data into arrays for each element. While achievable through a for-loop, I want to experiment with the map function.

Aluminium = measurements.map(function(row){
    return row.Aluminium;
});

The above code successfully creates an array for one element, but I desire a more flexible approach by passing the element name as a parameter.

function selectElement(elementname){
      measurements.map(function(row){
          return row.elementname;
      });
};

Aluminium = selectElement('Aluminium');
Iron = selectElement('Iron');

However, implementing this change has proven challenging, leaving me at a roadblock in my progress.

Answer №1

By utilizing Javascript, you have the ability to access children properties by specifying the key within square brackets. So instead of obj.key, you can use obj['key']

With this approach, the selectElement function can be modified as shown below:

function selectElement(elementname){
      measurements.map(function(row){
          return row[elementname];
      });
};

It is understood that elementname is a string which acts as a selector for the row object

Answer №2

row.elementname searches for a key containing the value "elementname". Using dot notation alone does not perform any evaluations. Remember to

function findElement(dataSet, elementname){
      return dataSet.map(function(row){
          return row[elementname];
      });
};

Gold = findElement(dataSet, 'Gold');
Silver = findElement(dataSet, 'Silver');

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