withNumericColumnFromRowValues method

DataFrame withNumericColumnFromRowValues({
  1. required String name,
  2. required num generator(
    1. Map<String, num> numericValues,
    2. Map<String, String> categoricValues
    ),
})

A new data frame with a numeric column calculated from row values.

Example:

final d = """
  number,base
  FF,16
  33,4
  AA,12
  10201,3
""".parseAsCsv(types: {"number": ColumnType.categoric});
print(d);
print(d.withNumericColumnFromRowValues(
  name: "decimal",
  generator: (numeric, categoric) => int.tryParse(
    categoric["number"]!,
    radix: numeric["base"]!.toInt(),
  )! as num,
));


.----.-------.
|base|number |
:----+-------:
|16  |FF     |
|4   |33     |
|12  |AA     |
|3   |10201  |
'----'-------'

.----.-------.-------.
|base|decimal|number |
:----+-------+-------:
|16  |255    |FF     |
|4   |15     |33     |
|12  |130    |AA     |
|3   |100    |10201  |
'----'-------'-------'

Implementation

DataFrame withNumericColumnFromRowValues({
  required String name,
  required num Function(
          Map<String, num> numericValues, Map<String, String> categoricValues)
      generator,
}) {
  if (!_columnNameOkay(name)) {
    throw PackhorseError.badColumnName(name);
  }
  return copy
    ..numericColumns[name] =
        NumericColumn(_numericRowValueResults(generator));
}