withNumericColumnFromTemplate method

DataFrame withNumericColumnFromTemplate({ required String name, required String template, required num generator(String), String startQuote = '{', String endQuote = '}', })

A new data frame with a numeric column generated from a template.

Example:

print(petals.withHead(5));
print(petals.withHead(5).withNumericColumnFromTemplate(
  name: "letters",
  template: "{species}",
  generator: (result) => result.length,
));

.--.------------.-----------.------------.
|id|petal_length|petal_width|species     |
:--+------------+-----------+------------:
|1 |1.4         |0.2        |setosa      |
|2 |1.4         |0.2        |setosa      |
|3 |1.3         |0.2        |setosa      |
|4 |1.5         |0.2        |setosa      |
|51|4.7         |1.4        |versicolor  |
'--'------------'-----------'------------'

.--.------------.-----------.-------.------------.
|id|petal_length|petal_width|letters|species     |
:--+------------+-----------+-------+------------:
|1 |1.4         |0.2        |6      |setosa      |
|2 |1.4         |0.2        |6      |setosa      |
|3 |1.3         |0.2        |6      |setosa      |
|4 |1.5         |0.2        |6      |setosa      |
|51|4.7         |1.4        |10     |versicolor  |
'--'------------'-----------'-------'------------'

Implementation

DataFrame withNumericColumnFromTemplate({
  required String name,
  required String template,
  required num Function(String) generator,
  String startQuote = '{',
  String endQuote = '}',
}) {
  if (!_columnNameOkay(name)) {
    throw PackhorseError.badColumnName(name);
  }

  return copy
    ..numericColumns[name] = NumericColumn(
      _templateResults(
        template,
        startQuote: startQuote,
        endQuote: endQuote,
      ).map(generator),
    );
}