Function getColumnsFromData

docs/tests/v2/es6/js/sanddance.js:147774–147787

* Derive column metadata from the data array. * @param data Array of data objects.

(data, columnTypes)

function getColumnsFromData(data, columnTypes) {
  const sample = data[0];
  const fields = sample ? Object.keys(sample) : [];
  const inferences = Object.assign(Object.assign({}, VegaDeckGl.base.vega.inferTypes(data, fields)), columnTypes);
  const columns = fields.map(name => {
    const column = {
      name,
      type: inferences[name]
    };
    return column;
  });
  inferAll(columns, data);
  return columns;
}
/**
 * Populate columns with type inferences and stats.
 * @param columns Array of columns.